1989 Ford Bronco II – From Diesel Experiment to 5.0L V8 Trail Rig
TRS forum member Northidahotrailblazer’s 1989 Bronco II is the kind of build that evolves the hard way—through real use, real breakage, and real-world problem solving.
What started as a Mercedes OM617 diesel swap eventually turned into something much more practical: a 5.0L V8-powered Bronco II backed by serious gearing, lockers, and a purpose-built suspension system designed to handle trails, road trips, and everything in between.
Mercedes OM617 Diesel Engine
From Diesel to V8
The build originally centered around a Mercedes OM617 diesel, but after dealing with cooling issues, lack of power, and the amount of fabrication required, the decision was made to scrap the diesel entirely.
In a single weekend, the drivetrain was pulled, sold, and replaced with a 5.0L V8 from a 1997 Ford Explorer. With a small block Ford transmission already in place, the swap made far more sense—and completely transformed the Bronco II.
Engine
- 5.0L V8 from 1997 Ford Explorer
- Factory fuel injection
- Explorer front accessory drive
- Swap-specific oil pan and filter adapter
The Explorer 5.0L brought:
- Significantly more horsepower and torque
- Better aftermarket support
- Simpler integration with existing drivetrain components
- Improved drivability both on and off-road
What started as a complicated diesel experiment suddenly became a much more refined and powerful build.
Axles, Gearing & Lockers
One of the biggest transformations in this build came from properly gearing the truck and adding lockers.
- Rear Axle: Ford 9-inch
- Gears: 5.13:1
- Locker: Detroit Locker
- Axle Shafts: Chromoly (28-spline)
- Rear Disc Brakes: Tom’s Offroad conversion
The rear axle was completely rebuilt, including setup bearings, backlash adjustment, and a fresh third member. After installation, the difference was immediate:
“I can’t explain how much this helped… I can use 5th gear now and it has plenty of power… it moves out so much better.”
- Front Axle: Dana 35 (TTB)
- Gears: 5.13:1
- Locker: Lock-Right (lunchbox locker)
- Knuckles / Spindles: 1994 F-150 Dana 44 knuckles, spindles, brakes, (to benefit from stronger Dana 44 hubs and bearing spacing)
- Locking Hubs: Warn manual locking hubs for 1994 Ford F-150 Dana 44
The front differential was rebuilt to match the rear with 5.13 gears and a locker, turning the Bronco II into a fully locked, properly geared trail rig.
Earlier in the build, a Dana 44 with 5.13s and a spool was considered (and even prepped), but the decision was made to continue developing the TTB setup instead.
The Ford 9-Inch axle provides the same 5×5.5 wheel bolt pattern used by the Dana 44 spindles up front.
Combined with proper gearing and traction upgrades, the truck is capable of tackling challenging trails while remaining usable on the street.
Suspension Setup
Rather than jumping straight into a solid axle swap, Northidahotrailblazer chose to build out the factory TTB (Twin Traction Beam) suspension.
Front Suspension
- TTB Dana 35 front axle
- Skyjacker lift brackets
- Extended / custom radius arms with Johnny Joints
- 4” lift coils (later replaced multiple times)
- Early Bronco 3.5” lift coils (testing for better flex)
- Wild Horses progressive coils (final iteration)
- James Duff coil bucket with shock mount
- Drop pitman arm
- Adjustable camber/caster bushings
The front suspension went through multiple revisions as he worked to balance ride quality and articulation. Early setups were too stiff and caused unloading on the trail, leading to several coil swaps until a better-performing combination was found.
“They are way too stiff and do nothing but unload… early Bronco coils work good.”
Rear Suspension
- 4-Inch Skyjacker leaf springs
- Lift blocks used to achieve full height
- Rear stance adjusted to match front lift changes
The rear suspension was adjusted multiple times to match the evolving front setup and maintain proper stance and drivability.
Transfer Case & Drivetrain
- Ford M5R2 manual transmission
- NP205 gear-driven transfer case
- ORD (Offroad Design) crawl box (doubler setup)
- Triple-stick shifters
The doubler setup provides excellent low-range gearing for crawling, though it required some dialing in to get the shifting feel right.
Wheels & Tires
- 35×12.50×15 Back Country Mud Terrain tires
- Fuel Off-Road Covert 15×8 bronze wheels (Switched from 10” wide wheels to 8” wide for better fitment)
On the Trail
This Bronco II isn’t theoretical—it’s been used hard.
- 400-mile round trip to the Inland Bronco Show (won Best Off-Road Bronco II)
- Whipsaw Trail in British Columbia
- Nevada backcountry / Pony Express Trail
- Regular rock crawling and trail runs
With lockers front and rear, 5.13 gears, and a doubler, the truck consistently performs well off-road:
“It went everywhere I pointed it.”
Like any real trail rig, it’s taken hits—bent brackets, axle issues, and suspension tweaks—but each trip has helped refine the build further.
Final Thoughts
Northidahotrailblazer’s Bronco II is a perfect example of building something the right way—not by following a plan, but by adapting when things don’t work.
The diesel experiment didn’t pan out. But what replaced it is a far more capable, usable, and proven rig:
- V8 power
- 5.13 gears
- Locked front and rear
- Dialed TTB suspension
- Trail-tested reliability
It’s not a showpiece—it’s a Bronco II that gets used exactly the way it was meant to.
Check out the full build thread here:
89 B2 Build Thread on The Ranger Station Forums
Photo Gallery
About The Author
Jim Oaks is a longtime Ford truck and SUV enthusiast and the founder of The Ranger Station and Bronco II Corral. With decades of hands-on experience, he writes both technical and non-technical articles covering the Ford Bronco II, including mechanical systems, factory engineering, common upgrades, and detailed feature vehicle write-ups.
In addition to technical content, Jim documents Bronco II history, rare factory and aftermarket models, production details, and original Ford marketing materials. His work is based on firsthand experience, original documentation, and long-term involvement in the Ford enthusiast community.
Through his sites, Jim has built comprehensive reference libraries that serve owners, builders, restorers, collectors, and historians, helping preserve the Bronco II’s technical knowledge and historical significance.
