FSB Ford Bronco Off-Road Build 5″ Lift, Super Duty Axles & 35s
The 70s cars seem to have gained rockstar status today, and the 1978–1979 Full-Size Bronco (FSB) is no exception. That said, keeping a 40-year-old rig not just driveable but truly trail-ready requires a lot of time and effort, although with the right parts and some technical knowledge you will definitely achieve this goal.
In this build overview, we’ll break down what it takes to make an old-school rig like this keep up with modern 4x4s, using Rustin’s 1978 Ford Bronco off-road build as an example. It sits on 35-inch tires, a 5-inch lift, and runs a modern Super Duty axle swap (if you have some experience with these trucks, then you may know that fitting modern 1-ton axles under a second-generation Bronco is quite a challenge, but more on that in the article).
We spoke directly with Rustin to find out what exactly he did with his stock 351M engine, how he custom-fabbed the drivetrain components, and how he turned this vintage Bronco into a reliable 4×4 rig. Whether you are researching a solid axle swap or just looking for stance inspiration, in this article you will find the complete blueprint of the build.
Key Build Features
- Vehicle: 1978 Ford Bronco (Full-Size/2nd Gen)
- Engine: Stock 351M with HEI Upgrade & 100-amp 1-wire alternator
- Suspension: 5-Inch Lift
- Axles: Ford Super Duty Axle Swap with Yukon 4.11 Gears
- Wheels & Tires: 17-inch wheels wrapped in 35-inch mud tires
- Key Mods: Custom Tom Woods driveshafts, Bronco Graveyard fuel tank, custom skid plate, American Autowire harness.
The Build
Fitting 35s: The 5-Inch Lift and Super Duty Axle Swap
Getting that ideal lifted truck look on a second-generation Full-Size Bronco (FSB) while keeping it off-road capable truly requires more than just a body lift.
Clearing massive 35-inch mud tires without causing binding or rubbing issues when the wheels are turned or when the suspension is compressed became possible thanks to the installation of a full 5-inch suspension lift with new shocks and springs, sitting on top of heavy-duty axles from modern Ford Super Duty trucks.
While the ’78 and ’79 Broncos came from the factory with pretty good Dana 44 solid front axles, modern Super Duty axles offer lots of advantages, such as a wider track width, a stronger housing, larger unit bearings, and much better durability.
Of course, installing those modern 1-ton axles on a vintage 40-year-old frame is quite a complex fabrication challenge, which requires precise geometry adjustments, custom fabrication of radius arm brackets, and track bar alignment. It didn’t stop the owner though, and he successfully completed all these tasks in his home garage.
A 1978 Bronco came with 29-inch tires from the factory, which is what modern crossovers are typically equipped with. Advanced 4×4 trails, on the other hand, require much larger tires to overcome obstacles. That’s why installing 35s is not really a styling move, but rather a pure necessity.
A 6-inch-larger tire obviously puts much more stress on the drivetrain and on the tired engine from the mid 70s. That’s why the owner decided to install tried-and-tested Yukon 4.11 gears that bring the final drive ratio back into alignment.
Another trick to reinforce the drivetrain is a set of custom Tom Woods driveshafts that are reinforced and slightly extended to ensure proper working angles from the transfer case down to the differentials.
351M Engine & Electrical
Under the hood of this ’78 Bronco is the classic Ford 351M V8 engine. It’s highly underpowered by modern standards, but pretty reliable and easy to work with (which matters a lot for a project like this). Rustin addressed the most common performance bottleneck of this engine by swapping out the failure-prone ignition for a modern HEI (High Energy Ignition) distributor.
This simple upgrade delivers a significantly hotter spark, ensuring crisp throttle response, smoother idle, and the cleaner combustion required to push those heavy 35-inch mud tires.
Because factory Ford wiring from the late ’70s is notoriously prone to brittle insulation, high resistance, and electrical gremlins, a simple replacement wasn’t going to cut it. That’s why the entire electrical setup was swapped for an American Autowire harness. It’s a far more reliable solution, built with modern safety standards in mind to protect against voltage drops and short circuits.
To round out the electrical upgrades and ensure the rig can handle auxiliary accessories without starving the battery, a high-output 100-amp 1-wire alternator was installed, balancing vintage character with modern, trouble-free reliability.
Q&A with the Builder
How did you become interested in off-roading?
– Started working for my company up in north west Colorado. There was a rock crawling course along with tons of BLM trails. Got hooked instantly. Now I’m back in Texas and it’s a goal to get it capable to make the drive back to Colorado, do some trails, and drive back.
Why did you choose this particular model for your project?
– Broncos have always been a favorite. Especially the 78-79 full size.
What inspired you to choose this modification style?
– I wanted something good for off-road and driving to work everyday
What challenges did you face while putting it together?
– Well, being a 40 year old truck it’s constantly fighting me. But with each fix I learn something new.
What do you love about your vehicle?
– Turning heads is one of the great things about driving a classic
Is it your daily or a weekend ride?
– Weekend ride right now
Do you take it off road? If so, where and how often?
– Every time I get the chance. Unfortunately not as much as I would like
1978 Ford Bronco Specs
Engine specs, modifications
– Stock 351M with HEI and 100amp 1 wire alternator
Lift height and suspension modifications
– 5 inch lift on top of SUPERDUTY axles
Wheel specs
– 17 inch wheels with 35s
All other mods
– American Autowire wiring harness
– Auto Meter gauges
– Yukon 4.11 gears
– Custom Tom Woods driveshafts
– Bronco Graveyard fuel tank
– Custom skid plate
What are your future plans about this vehicle?
– Get it back on the road! I have a few electrical issues to tidy up on. Then moving to lockers and eventually an engine swap.
The Appeal of the 1978-1979 Second-Gen Bronco
The second-generation Ford Bronco based on the F-100 was introduced to the market in 1978 after years of planning, development, and delays caused by the oil crisis. It was a completely new full-size SUV designed to compete with Chevy, Dodge, and Jeep offerings.
The vehicle came with a powerful V8 engine and an updated part-time 4WD system. It had a foldable rear seat and a removable hardtop, and after lowering the power rear window, you could drop the tailgate. That made the Bronco not only sporty and capable in the off-road environment but also gave it unprecedented utility, which explains why the model was so popular in 1978-1979.
Due to the years of delays before its release, the second-generation Ford Bronco’s design appeared somewhat dated back in the day, but now it gives the vehicle an even classier look. Even though this version of the Bronco was in production for only two years, the sales were very solid.
Today, on the open market, baseline 1978 Ford Broncos range widely from $3,000 to $10,000 for rusted, non-running projects up to $75,000 to $176,000+ for concours-grade collector examples, with solid weekend drivers averaging $25,000 to $55,000.
When a truck is heavily modified with custom restomod upgrades like a Super Duty axle swap, lift, and specialized drivetrain components, completed builds can be priced between $45,000 and $80,000+ on the resale market.
| Category / Condition Tier | Market Price Range & Description |
| Project / Rusted / Non-Running (Stock) | $3,000 – $10,000 | Heavily weathered barn finds, severe frame/body rust, non-running engines, or rolling chassis restoration projects. |
| Average Market Baseline (Good/Excellent Stock) | $25,000 – $55,000 | Solid, running weekend drivers with decent paint and minor wear (common on platforms like Bring a Trailer). |
| Concours / Restored Collector Grade (Stock) | $75,000 – $176,000+ | Pristine, numbers-matching “Free Wheeling” option packages, high-end frame-off restorations, or rare Ranger XLTs at live auctions. |
| Fully Modified / Restomodded (Custom Build) | $45,000 – $80,000+ | Custom fabrication (lifts, 1-ton axles, gearing, wiring) built as a rugged trail or weekend custom rig. |
| Elite Professional Restomods | $100,000 – $190,000+ | High-end custom shop builds featuring modern Coyote V8 engine swaps, custom leather interiors, and flawless paint. |
Why restoring it this way matters
Beased on our off-road build rating this rig scores 55 points (30 points for the 4×4 layot and heavily oversized wheels and lift, 10 points for the rear LSD in rear Ford 9″ axle, 10 for low range and 5 for body-on-frame layout).
Vintage 4x4s have one big advantage – their tech is far easier to work on, but on the downside, they struggle to keep up with modern SUVs in terms of reliability and performance.
This build shows step by step what needs to be done to a 40-year-old Full-Size Bronco to turn it into a capable trail rig, so if you are toying with the idea of restoring one of these on a budget and using it for off-roading, this build may be the ultimate blueprint to follow.
With a realistic parts investment ranging between $4,880 and $10,000+ (excluding custom fab and labor) and current market prices for running examples, building a rig like this makes total sense, as it will only appreciate in value. Add a quality paint job and interior work, and you’ve got yourself an appreciating asset with a high level of emotional return.
| Component / Upgrade | Estimated Cost Range (Parts Only) |
| Donor Super Duty Axles (Front & Rear Sourced Used) | $800 – $1,500 |
| Super Duty Axle Swap / Conversion Bracket Kit | $400 – $2,400 |
| 5-Inch Suspension Lift Kit (Coils, Leafs & Hardware) | $1,000 – $2,200 |
| Yukon 4.11 Ring & Pinion Gears + Install Kits | $800 – $1,200 |
| Custom Tom Woods Driveshafts (Front & Rear) | $1,200 – $1,600 |
| HEI Distributor Upgrade (351M/400) | $180 – $250 |
| American Autowire Universal Harness Kit | $350 – $550 |
| 100-Amp 1-Wire High-Output Alternator | $150 – $300 |
| Total Estimated Parts Investment | $4,880 – $10,000+ |
Related Parts & Mods
– Inspired by this Ford Bronco build and looking to prepare your own vintage 4×4 for off-road adventures? Our team has put together a list of products and accessories available online that may help you to achieve similar results:
Ignition & Electrical
- A-Team Performance HEI Distributor – For Ford 351C, 351M, 400M, 429 & 460 V8 *One-wire installation, 65K-volt coil, CNC-machined shaft and chrome moly gear
- Tuff Stuff 7068 Alternator, 100 Amp 1-Wire – Single V-belt pulley, aluminum case *The same 100-amp 1-wire spec used in this build
Gauges
- Auto Meter 1650 5-Piece Gauge Kit – GPS speedometer, oil pressure, water temperature, voltmeter and fuel level *Senders and mounting hardware included, no calibration required
Wheels & Tires
- Crosswind M/T 35X12.50R17, Load Range E 10-Ply – Matches the 17-inch wheel and 35-inch tire setup on this Bronco *Requires a 5-inch lift or equivalent clearance, and re-gearing is strongly recommended
Axles & Gearing
- Yukon PK D60-F Pinion Install Kit – For Dana 60 front differentials *Includes pinion bearings and races, crush sleeve, shim kit, pinion nut and marking compound — verify rotation direction, as Super Duty front axles are reverse-rotation
Roof Top Tent
- Roofnest Evo 3 Air Roof Top Tent – For those who want to take the overlanding route *Sleeping space is truly limited inside a 2-door full-size Bronco
*Always verify product compatibility for your specific vehicle with a seller before purchase. Specs and fitment may vary by model, year, and trim level. We are not responsible for fitment or other issues that may arise from using the products listed above.
Watch the progress and find out more about this Ford Bronco project by visiting the Instagram profile of the owner: @vivid_retro_customs!
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