F-100 4x4 Conversion: Add 4WD to Your Truck

Why Convert Your F-100 to Four-Wheel Drive?

Most Ford F-100s left the factory as two-wheel-drive trucks. Ford did offer 4x4 versions starting in 1959, but they were a small fraction of total production and command steep premiums today. If you want your F-100 to handle dirt roads, ranch work, mud, or trail use, converting a 2WD truck to 4WD is often more practical and less expensive than buying a factory 4x4.

A 4x4 conversion also opens up build possibilities that a stock truck cannot match. You can pair a modern transfer case with a built engine and upgraded suspension to create a truck that performs far beyond what Ford offered in the 1960s and 1970s. And unlike a factory 4x4 F-100 that has been through fifty-plus years of off-road abuse, a freshly converted truck starts with components you have inspected, rebuilt, or purchased new.

The conversion is an advanced project. It requires fabrication skills, a solid understanding of drivetrain geometry, and significant time under the truck. But the community has been doing these builds for decades, and bolt-on kits from companies like Kincer Chassis have reduced the fabrication barrier considerably for 1965-1979 trucks.

Three Approaches to 4WD Conversion

There is no single way to add four-wheel drive to an F-100. The right approach depends on your budget, your generation of truck, and how much fabrication work you want to do. Here is a comparison of the three most common methods.

	Bolt-On Kit	Donor 4x4 Frame Swap	Component Build
Best for	1965-1979 trucks	Any generation	Builders with fabrication skills
Cost range	$1,400-$11,000 (kit only)	$3,000-$8,000 total	$2,000-$6,000 total
Time estimate	80-120 hours	100-200+ hours	120-200+ hours
Fabrication required	Minimal to moderate	Moderate (body mount alignment)	Extensive
Primary advantage	Engineered fitment, instructions included	Proven 4x4 frame with correct geometry	Maximum flexibility and lowest parts cost
Primary drawback	Limited to supported year ranges	Requires a body-off frame swap	No instructions; you are the engineer

Approach 1: Bolt-On Conversion Kit (Kincer Chassis)

Kincer Chassis, in partnership with Krawlers Edge, offers the most complete bolt-on 2WD-to-4WD conversion kit for Ford trucks. Their kits cover 1965-1979 F-100, F-150, F-250, and F-350 models and are available in three tiers.

Kit One — The Basics ($1,400 range). This kit includes the frame conversion components: front coil spring buckets, shock mounts, frame boxing reinforcements, track bar mount, and engine crossmember modifications. You source your own front axle, transfer case, driveshafts, and springs. This tier is for builders who already have donor components or want to choose their own axle and transfer case combination.

Kit Two — The Advanced Setup (mid-range pricing). Adds more drivetrain-specific components to the basic frame kit, reducing the number of parts you need to source independently.

Kit Three — The Complete Kit ($11,000 range). Includes a fully assembled front axle and everything needed to get the truck rolling in 4WD. This is the turnkey option for builders who want to minimize parts hunting.

All three tiers are designed to work with the 2WD frame rails, so you do not need to swap to a 4x4 frame. The kit modifies your existing frame to accept 4WD components. Kincer and Krawlers Edge built their reputation on early Bronco chassis (including a build for Jay Leno’s Bronco shown at SEMA 2019), and their F-series kits apply the same engineering approach.

Who this is for: Builders with 1965-1979 trucks who want engineered, tested fitment without designing everything from scratch. The basic kit is affordable enough that it competes with the component-build approach while eliminating the guesswork on frame modifications.

Approach 2: Donor 4x4 Frame Swap

If your truck falls outside the 1965-1979 range or you want a frame that was designed from the factory for 4WD loads, swapping your 2WD body onto a 4x4 frame is a proven path. The process is essentially the same as a standard frame swap, except you are sourcing a 4x4 donor frame instead of a 2WD one.

The 4x4 frame is structurally different from the 2WD version. Ford reinforced the 4x4 frame rails with additional crossmembers and stiffer sections to handle the loads from the front axle, transfer case, and front driveshaft. You cannot simply bolt a front axle onto a 2WD frame without significant reinforcement — the 4x4 frame already has all of that built in.

Best donor frames:

• 1973-1979 F-100/F-150 4x4 frame: Direct fit under 1973-1979 truck bodies with matching wheelbase. If you have a sixth-generation (1973-1979) truck, this is the simplest donor match.
• 1978-1979 Ford Bronco frame: The full-size Bronco shares the same platform as the 1967-1979 F-100/F-150, and every Bronco came with 4WD. Bronco frames are often less expensive than F-series 4x4 frames because there is less demand from the F-100 community. The wheelbase is shorter (104 inches vs. the F-100’s 117-133 inches depending on bed length), which works under short-bed trucks but not long-beds without modification.
• 1966-1972 F-100 4x4 frame: Matches fourth- and fifth-generation truck bodies. Less common at salvage yards than 1973-1979 frames.

The donor frame approach costs $1,500 to $4,000 for the frame itself (more if it comes with a running drivetrain), plus the same body mount fabrication, wiring, and reassembly costs as any frame swap.

Who this is for: Builders with pre-1965 trucks that no kit covers, trucks with badly rusted frames that need replacement anyway, or anyone who wants factory 4x4 frame geometry without fabrication.

Approach 3: Component-by-Component Build

This is the traditional hot-rodder approach: source individual components from salvage yards, swap meets, and online marketplaces, then fabricate the mounts and brackets to make everything fit your specific truck. It offers the most flexibility but requires the most fabrication skill and problem-solving.

You will need to acquire a front axle, transfer case, 4x4 transmission (or adapter), front and rear driveshafts, leaf springs or coil springs, steering linkage, and all associated hardware. You will also need to reinforce your 2WD frame rails in the areas where 4x4 components mount.

Who this is for: Experienced fabricators building a one-off truck, builders working with unusual generation or engine combinations, and anyone who enjoys the hunt for parts as much as the build itself.

Key Components for the Conversion

Regardless of which approach you choose, you need the same core components. Here is what each one does and what to look for.

Front Axle

The front axle is the most important single component in the conversion. It must be the correct width for your truck, strong enough for the weight and intended use, and compatible with your steering and brake setup.

Dana 44: The most common front axle in factory 4x4 F-100s. Ford used the Dana 44 from 1959 through 1979 in half-ton trucks. There are two distinct designs:

• Closed knuckle (1959-1966): Uses enclosed ball-shaped knuckles at each end with grease-packed bearings. Stronger and more sealed against dirt and water, but heavier and harder to service. Parts are available from specialists like Torque King and Denny’s Driveshaft.
• Open knuckle with king pins (1967-1979): Ford switched to open knuckles but retained king pins and knuckle bearings rather than ball joints. This is an unusual design, as most open-knuckle axles use ball joints. Parts are still available but require Ford-specific sourcing.

Dana 60: Used in F-250 and heavier trucks. Significantly stronger than the Dana 44, with full-floating hubs. Overkill for a half-ton F-100 unless you plan serious off-road abuse or are running a high-horsepower engine. The Dana 60 is wider than the Dana 44, which may require fender modifications.

Early Bronco Dana 44 (1966-1977): A popular donor axle because early Broncos are plentiful in salvage yards and the axle width is close to the F-100’s front track. You will need to remove track bar mounts and add leaf spring perches if your truck uses leaf springs.

Transfer Case

The transfer case splits power between the front and rear axles. Your choice depends on how you plan to use the truck.

NP205 (New Process 205): The gold standard for durability. This is a cast-iron, gear-driven, part-time transfer case weighing approximately 140 pounds. Ford used the NP205 in 1973-1979 F-100/F-150, 1978-1979 Bronco, and various F-250/F-350 models. The low range ratio is 1.96:1 — shallow by modern standards but adequate for most trail use. The NP205 is nearly indestructible and the preferred choice for heavy trucks or any build where reliability matters more than weight. Expect to pay $300 to $800 for a good used unit.

BW1345 (Borg Warner 1345): An aluminum, chain-driven transfer case weighing 85 to 90 pounds with a 2.48:1 low range. Ford used it in 1981-1986 trucks. Lighter and quieter than the NP205, with a deeper low range. The chain can stretch under sustained heavy torque, but for moderate off-road use and daily driving, the BW1345 is a solid choice. Less expensive than the NP205, typically $200 to $500 used.

BW1356 (Borg Warner 1356): Similar to the BW1345 but with an electric shift motor for push-button 4WD engagement. Used in later 1980s Ford trucks. A good option if you want the convenience of electronic shifting, but the shift motor and vacuum system add complexity.

NP208: A lighter-duty chain-driven case primarily associated with GM trucks. While it appeared in a small number of Ford applications, Ford primarily used the BW1345 and BW1356 in this era. The NP208 is adequate for light off-road use but not as durable as the NP205 or BW1345. Generally not recommended for a conversion build when better Ford-compatible options are available for similar money.

Transmission

Your existing 2WD transmission will not work with a transfer case because it lacks the output configuration to mate with one. You need either a 4x4 version of your transmission or an adapter.

Manual transmissions: The NP435 four-speed is the most common manual paired with the NP205 in Ford trucks. It is a granny-low truck transmission with an extremely low first gear (6.69:1), and the truck is really a three-speed-plus-granny in daily driving. The T-18 four-speed is another option with a more usable first gear ratio. Both bolt directly to the NP205 with the correct adapter housing.

Automatic transmissions: The C6 three-speed automatic is the most common match for the NP205 in Ford trucks. Ford also paired the C4 with smaller engines. For 1980s trucks, the AOD four-speed overdrive can be adapted to the BW1345.

Adapter kits: Companies like Advance Adapters sell adapter housings that mate various transmissions to various transfer cases. If you want to run a specific engine and transmission combination that Ford never offered with 4WD, an adapter kit is likely available.

Driveshafts

You will need two driveshafts: one from the transfer case to the front axle, and one from the transfer case to the rear axle. Both will almost certainly need to be custom length. A local driveline shop can measure, build, and balance custom shafts for $200 to $400 each. Do not skip the balancing. An unbalanced driveshaft causes vibrations that destroy U-joints and transfer case seals.

Steering Modifications

This is one of the most overlooked aspects of a 4x4 conversion. On a 2WD F-100, the steering gear sits behind the front axle. On a 4WD F-100, the steering gear sits in front of the axle, and the entire linkage geometry changes. You will need:

• A 4x4 steering gear box (or the complete setup from your donor vehicle)
• A drag link and tie rod sized for the front axle
• Modification to the driver-side inner fender. Ford trimmed the bottom edge on factory 4x4 trucks to clear the intermediate shaft and steering gear, and you will need to do the same
• Potentially a new steering shaft with universal joints to handle the angle change through the firewall

Test the steering through its full range of travel — lock to lock — before finalizing anything. Binding in the steering system is dangerous and must be resolved before the truck moves under its own power.

Springs and Suspension

The suspension setup depends on your truck’s generation and the front axle you choose.

Leaf spring trucks (1948-1965, 1973-1979): These generations used leaf springs at all four corners on 4x4 models. You need leaf springs rated for the weight of the front axle and a set of spring perches welded to the axle housing. Spring packs from a donor 4x4 truck are the easiest source. Aftermarket springs from companies like General Spring and Performance Online are available for most year ranges.

1966-1972 trucks: Factory 4x4 F-100s in this era retained leaf spring solid front axles. The 2WD Twin I-Beam (1965+) used coil springs, but 4WD models did not. The Kincer Chassis kit includes coil spring buckets as an aftermarket conversion option for builders who want coil spring front suspension on their 4x4 build. If building from components with factory-style leaf springs, you need spring perches welded to the axle housing and springs rated for the front axle weight.

Seventh generation (1980-1983): These trucks used Twin I-Beam independent front suspension on 2WD models and TTB (Twin Traction Beam) on 4WD models. The TTB components bolt to the same mounting points as the 2WD IFS, making this the easiest generation to convert. The 2WD tie rods even work with the TTB front end.

For a deeper look at suspension components and lift options, see the suspension upgrades guide.

Generation-by-Generation Compatibility

Not every F-100 generation is equally suited for a 4x4 conversion. Here is a realistic assessment of each.

Generations 1-2 (1948-1956): Challenging

Ford did not offer a 4x4 F-100 in these years, so there is no factory template to follow. You are working from scratch: fabricating axle mounts, modifying frame crossmembers, and engineering the entire drivetrain layout. An early Bronco Dana 44 front axle is close to the right width, but you will need to fabricate leaf spring perches and all mounting hardware. These builds are doable but require advanced fabrication skills and significant planning. A complete frame swap onto a later 4x4 frame is often the more practical route for these early trucks.

Generation 3 (1957-1960): Challenging

Similar situation to Generations 1 and 2. Ford introduced the 4x4 option in 1959, but donor 4x4 frames from this era are extremely rare. Most builders either fabricate from scratch or swap the body onto a later 4x4 frame with custom body mounts.

Generation 4 (1961-1966): Moderate

Factory 4x4 frames exist for 1961-1966 trucks, though they are uncommon at salvage yards. The Dana 44 closed-knuckle front axle was used in these years. If you can find a donor 4x4 frame, the body swap is straightforward since the body mounts are the same. The Unibody trucks (1961-1963) add a complication because the cab and bed are integrated with the frame — you cannot do a simple body-off swap.

Generations 5-6 (1967-1979): Easiest

This is the sweet spot for 4x4 conversions. The Kincer Chassis bolt-on kits cover 1965-1979 trucks. Donor 4x4 frames from F-100s, F-150s, and Broncos are the most plentiful from this era. The Dana 44 open-knuckle front axle, NP205 transfer case, and NP435 or C6 transmissions are all readily available. Parts interchange between the F-100, F-150, and full-size Bronco is extensive, giving you the widest possible parts pool.

The 1973-1979 Dentside trucks are the single easiest generation to convert because the 4x4 version was the most popular and donor parts are abundant.

Generation 7 (1980-1983): Moderate to Easy

The TTB front suspension on 4WD models bolts to the same frame mounting points as the 2WD independent front suspension. This makes the mechanical conversion relatively straightforward. The challenge is that the F-100 was 2WD only in this generation — all 4WD trucks were F-150s. You need F-150 4x4 TTB components, a transfer case, and a 4WD transmission. The parts are plentiful since Ford produced millions of 1980-1986 F-150 4x4s.

The Bronco Donor Strategy

The 1978-1979 full-size Ford Bronco deserves special mention because it shares the same platform as the 1967-1979 F-series trucks and every Bronco came equipped with 4WD. A single Bronco donor can supply your front axle (Dana 44), transfer case (NP205), 4WD transmission, front driveshaft, steering components, and leaf springs — essentially everything you need except the frame modifications.

Bronco donors are often cheaper than equivalent F-series 4x4 donors because the Bronco market is separate from the F-100 collector market. A complete running Bronco in rough cosmetic condition can be found for $2,000 to $5,000, giving you a parts truck with everything you need.

When buying a Bronco for parts, note that all Bronco transfer cases use fixed yokes (not slip yokes), which affects driveshaft configuration. Also verify the axle width, as the Bronco’s shorter wheelbase means the front axle width may differ slightly from the F-100’s, depending on the year.

The early Ford Bronco (1966-1977) is a separate vehicle on a shorter wheelbase and does not share the F-series frame. However, early Bronco Dana 44 front axles are popular swap candidates because they are approximately the right width for an F-100 and widely available.

Parts Sourcing Guide

Finding the right components at reasonable prices requires looking in multiple places.

Salvage yards: Your best source for complete donor assemblies. Look for 4x4 F-100s, F-150s, and Broncos from the same era as your truck. Pull the front axle, transfer case, transmission, driveshafts, steering box, and springs as a package so you know everything matches. Expect to pay $500 to $2,000 for a complete front axle assembly and $300 to $800 for a transfer case.

Online marketplaces: Facebook Marketplace, Craigslist, and eBay are all productive sources. Search for “F100 4x4 parts,” “F150 4x4 front axle,” “NP205 Ford,” and “Bronco 4x4 parts.” Join Ford truck Facebook groups and watch for members parting out 4x4 trucks.

Swap meets: Carlisle, Hershey, and regional Ford-specific swap meets often have vendors with axles, transfer cases, and drivetrain components. Prices can be better than online because sellers do not want to haul heavy parts home.

Specialty suppliers:

• Kincer Chassis / Krawlers Edge: Conversion kits and engineered components for 1965-1979 trucks
• Torque King: Dana 44 rebuild kits, king pin kits, hub components, and NP205 parts for 1966-1979 Ford trucks
• Denny’s Driveshaft: Dana 44 axle shafts, U-joints, and driveshaft components
• Advance Adapters: Transmission-to-transfer-case adapter housings for non-standard combinations
• Dennis Carpenter / LMC Truck: Steering components, body hardware, and general restoration parts

Forum classifieds: Fordification.com, Ford Truck Enthusiasts, and Slick 60s all have classifieds sections where members sell parts from project trucks. These are often the best-priced source for rare components because sellers know exactly what they have.

Cost Breakdown

Component	Budget (Junkyard/Used)	Mid-Range (Kit + Used)	Premium (Complete Kit)
Conversion kit or frame modifications	$200-$500 (DIY fab)	$1,400-$3,500 (Kincer Kit 1-2)	$8,000-$11,000 (Kincer Kit 3)
Front axle (Dana 44)	$500-$1,200	Included or $500-$1,200	Included
Transfer case (NP205)	$300-$800	$300-$800	Included
4WD transmission	$300-$700	$300-$700	$300-$700
Driveshafts (2 custom)	$400-$800	$400-$800	$400-$800
Springs and shocks	$200-$500	$200-$500	Included
Steering conversion	$200-$500	$200-$500	$200-$500
Brake components	$150-$400	$150-$400	$150-$400
Miscellaneous hardware	$200-$400	$200-$400	$200-$400
Total (DIY labor)	$2,500-$5,800	$3,700-$8,800	$9,500-$14,000+

If you hire a shop for the fabrication and installation, add $3,000 to $8,000 in labor depending on your area and the scope of work.

Common Challenges and Pitfalls

Underestimating the steering conversion. The steering system differences between 2WD and 4WD trucks are more extensive than most builders expect. The gear box, drag link, tie rod, and inner fender all need to change. Bolting in a front axle without addressing the steering first leaves you with a truck that cannot turn properly.

Skipping frame reinforcement. A 2WD frame was not designed for the loads that a front axle, transfer case, and front driveshaft impose. If you are not using a kit that includes boxing plates and reinforcements, you must add your own. Use 3/16-inch steel plate minimum and weld continuously along the rails in the mounting areas. Tack welds will crack.

Wrong driveshaft angles. The relationship between the transfer case output angle and the axle pinion angle must be within a few degrees of each other, or you will get vibrations, premature U-joint wear, and noise. Measure the angles with an inclinometer before and after installation. A driveline shop can advise on the correct operating angle for your specific setup.

Ignoring the transmission swap. Some builders focus on the axle and transfer case and forget that their 2WD transmission will not mate to a transfer case. Budget for a 4WD transmission or an adapter kit from the start.

Mismatched gear ratios. The front and rear axle gear ratios must be identical. If your rear axle has 3.50:1 gears and your donor front axle has 3.73:1 gears, the transfer case will bind in 4WD. Regearing one axle to match the other adds $300 to $600 but is not optional.

Not planning the shifter routing. The transfer case shift lever needs to reach the cab interior. On a floor-mounted transfer case like the NP205, this means cutting a hole in the floor and fabricating a shifter boot and bezel. Plan the location before you finalize the transfer case position.

Using a worn donor axle without rebuilding. A junkyard front axle with worn king pins, loose wheel bearings, or a cracked housing will create problems from day one. Budget for a rebuild — new king pin kits, wheel bearings, and seals — before you install the axle. This adds $200 to $500 in parts but prevents headaches later.

Frequently Asked Questions

How much does an F-100 4x4 conversion cost?

A budget 4x4 conversion using junkyard components and DIY fabrication costs $2,500 to $5,800 in parts. A mid-range build using a Kincer Chassis basic kit with used drivetrain components runs $3,700 to $8,800. A premium build with the complete Kincer kit and new components can reach $9,500 to $14,000 or more. Shop labor adds $3,000 to $8,000 on top of parts costs, depending on complexity and your area.

Which F-100 generations are easiest to convert to 4x4?

The 1967-1979 trucks (generations 5 and 6) are the easiest to convert because the Kincer Chassis bolt-on kit supports them, donor 4x4 frames and components from F-100s, F-150s, and Broncos are abundant, and the community has documented these builds extensively. The 1980-1983 generation is also relatively easy because the 4WD TTB front suspension bolts to the same frame mounting points as the 2WD independent front suspension.

Can I bolt a front axle onto my 2WD frame without modifications?

No. The 2WD and 4WD frames are structurally different. The 4WD frame has additional crossmembers, reinforced sections, and specific mounting points for the front axle, transfer case, and front driveshaft. Converting a 2WD frame requires either a bolt-on kit (like the Kincer Chassis kit for 1965-1979 trucks) that adds the necessary reinforcements, or custom fabrication to box the frame rails and add mounting brackets. Simply bolting an axle to an unmodified 2WD frame is unsafe.

What transfer case should I use for an F-100 4x4 conversion?

The NP205 is the most durable option: a cast-iron, gear-driven transfer case that is nearly indestructible. It weighs 140 pounds and has a 1.96:1 low range. Ford used it in 1973-1979 F-100/F-150 and 1978-1979 Bronco trucks. For a lighter build or daily driver, the BW1345 is an aluminum, chain-driven alternative weighing 85 to 90 pounds with a 2.48:1 low range. The BW1345 is quieter and lighter but its chain can stretch under sustained heavy torque.

Do I need to change my transmission for a 4x4 conversion?

Yes. A 2WD transmission does not have the correct output configuration to connect to a transfer case. You need either a 4x4 version of your transmission (which has a shorter output shaft and a mounting face for the transfer case) or an adapter kit from a company like Advance Adapters. The NP435 four-speed manual and C6 three-speed automatic are the most common pairings with the NP205 transfer case in Ford trucks.

Is a 1978-1979 Bronco a good parts donor for an F-100 4x4 conversion?

Yes. The full-size 1978-1979 Bronco shares the same platform as the 1967-1979 F-series and every Bronco came with 4WD. A single Bronco can supply the front axle (Dana 44), NP205 transfer case, 4WD transmission, front driveshaft, steering components, and leaf springs. Bronco donors are often cheaper than equivalent F-series 4x4 donors. A rough-condition running Bronco costs $2,000 to $5,000, providing nearly every component you need for the conversion.

Will my front and rear axle gear ratios need to match?

Yes, and this is not optional. The front and rear differential gear ratios must be identical. When both axles are engaged in 4WD, mismatched ratios cause the transfer case to bind because the front and rear driveshafts are trying to spin at different speeds. If your rear axle has 3.50:1 gears and your donor front axle has 3.73:1 gears, you must regear one axle to match the other. Regearing costs $300 to $600 per axle at a differential shop.

How do the steering changes work for a 4x4 conversion?

On a 2WD F-100, the steering gear sits behind the front axle. On a 4WD version, it sits in front of the axle, and the entire linkage geometry is different. You need a 4x4 steering gear box, a new drag link and tie rod, and modifications to the driver-side inner fender to clear the intermediate shaft. Ford trimmed the bottom edge of the 4x4 inner fender on the assembly line, and you need to duplicate that clearance cut. A new steering shaft with one or two universal joints handles the angle change through the firewall.

Plan Your Build

A 4x4 conversion is one of the most rewarding upgrades you can do to an F-100, but it touches nearly every system on the truck. Before you start pulling parts, map out your full build plan and budget. These guides cover the other major decisions you will face along the way:

• Daily Driver Build Guide — how to build an F-100 that handles modern roads and daily use
• Restoration Cost Guide — realistic budgets for every level of F-100 build
• First Project Truck Guide — what to look for when buying an F-100 and how to prioritize your first upgrades