Click for Coverage
Exclusive Content
Original Shows, Motorsports and Live Events
Try it free for 14 days
Due to the EU’s Global Data Protection Regulation, our website is currently unavailable to visitors from most European countries. We apologize for this inconvenience and encourage you to visit for the latest on new cars, car reviews and news, concept cars and auto show coverage, awards and much more.MOTORTREND.COM
  • JP Magazine
  • Dirt Sports + Off-Road
  • 4-Wheel & Off-Road
  • Four Wheeler

Dropping a Willys on a Wrangler

Posted in How To: Body Chassis on May 3, 2017
Share this

Sometimes a project requires hitting the restart button. I found this Red 1961 Willys Wagon in a garage where it had sat since 1978 with a blown Ford Y-block V-8 engine (by “blown” I mean blown apart, not supercharged—it literally had a hole in the side). I drug it home and did a new V-8 swap in record time for a video, but in doing so the Jeep could go but not really stop, as we had adapted a new V-8 to the tired old drivetrain. The steering wasn’t great, the gearbox was leaking, and both old axles were due for a rebuild. Plus there was a giant hole where the firewall had been because I didn’t have time to finish it. One night I was trying to move it around the workshop and it ran into another vehicle because of the lack of brakes. It wasn’t bad, but I was annoyed with this cool-looking Jeep with a nice new engine that was still undrivable. I parked it and stewed on it for almost a year.

I decided to start over. The V-8 was great but would require an all new drivetrain. If I was going for a new drivetrain, I might as well just swap a later-model Jeep under the Red Wagon. I’d seen it done by the Mopar Underground with a TJ Wrangler Unlimited frame and drivetrain, and the resulting 4.0L Wagon was a good all-around Jeep.

I was soon on the hunt for an LJ or TJ but instead found a 1993 YJ that had been wrecked. The price was good, and it had a 4.0L, an AX15 five-speed, and an NP231 T-case. The YJ suspension is easy to upgrade with better springs and shocks to clear bigger tires and support the heavier Wagon body. The YJ axles aren’t spectacular, but I knew where to get axles better than new. As for that V-8 I was pulling out of the Wagon, well, I have no shortage of ideas for where that can live (hint: future projects!).

The Red Wagon was rebuilt in record time again with plenty of help from my friend and cohost on our web show, Dirt Every Day, Dave Chappelle. The result turned out better than ever. We now have four-wheel disc brakes. We have a rugged, reliable fuel-injected straight-six engine. And the leaf-sprung suspension is simple and rides well. The Red Wagon is ready to make up for all that time it was sitting in a garage getting dusty. Now it’s time to go get it dirty.

This is how the 1961 Willys Wagon sat for roughly 37 years. The prior owner had driven it in high school and on surfing trips. There was a Ford Y-block V-8 under the hood, but when it ventilated the block with a piston the Wagon got parked. My goal was to bring it back to daily driver glory but not modify it too much from looking stock.
Build No. 1 was a Chevy V-8 swap done at Advance Adapters. We mated a 4.8L LS truck engine to the stock three-speed T-90 transmission with an adapter. It was fun and worked, but the brakes, steering, suspension, and axles were all tired. It was time for a new outlook on what this Jeep should be.
Build No. 2 involved the Red Wagon and a smashed 1993 YJ. This would give the Wagon a Jeep engine again, and the LS would find a new home in something else. The Wagon isn’t going to be a tire smoker, but it will be a fun dirt-road-wheeling and camping rig.
Step 1 was to remove all the old wrecked stuff from the YJ. A new Bend Pak lift in my shop made this step pretty awesome. The body was raised and the frame rolled outside for a thorough pressure washing. The body, though pretty smashed, still had good parts that my friends all scavenged for their projects.
Next, the wagon body was removed from the wagon chassis. Everyone thought I was crazy at this point for pulling out a good-running Chevy V-8 for a 4.0L straight-six. Even I had once said, “Never swap in a 4.0L!” But now, I argued, I wasn’t swapping in a 4.0L, but rather swapping in all the good drivetrain around the 4.0L and the 4.0L was just coming along for the ride. Plus, the V-8 will find a new home in another project.
Upon closer inspection we found that the YJ had a bad frame twist. There was an upward bend on the passenger side that we had not seen upon purchase. This was less than ideal, but we decided to try and fix it with a bottle jack, some big clamps, and a heavy piece of I-beam. Eventually we cut and plated it back to almost straight. Learn from us: Be sure the frame is good when you buy a donor for a project like this.
Getting the Wrangler chassis with a 93 1/2-inch wheelbase to fit the Willys Wagon with a 104-inch wheelbase would require some stretching. We picked a flat parallel section of frame in front of the rear leaf springs and cut the chassis square.
Then Chappelle sleeved the frame with smaller 2x3 box tubing. We used a number of big clamps and more square tube to keep everything straight and true. Afterwards Chappelle boxed in the frame and added an internal fishplate for strength.
Once the frame was the correct length we rolled it under the body. We spaced the body off the frame enough to clear the drivetrain, and then Chappelle started building body mounts. Using rectangular tubing and Daystar body bushings, he built 14 mounts from the frame to the body using the factory body mounting points. All the factory YJ frame mounts were removed prior.
Because of the bent frame and the old Jeep body we found the mounts were not identical side-to-side but very close. However, adjustments had to be made to get all the old components to align. In the end the body mounts and frame stretch are clean and look almost factory, if not better.
With the body off the frame we did some repairs to the 4.0L. The rear main seal was replaced, as were the clutch and all the fluids. The factory alternator and A/C compressor had been damaged in the wreck, so new components were order up from and used mounts were sourced to attach them. Luckily the block was still solid. We also replaced the motor mounts with Daystar units.
The Jeep’s NP231 T-case was pulled off and rebuilt with a new slip-yoke eliminator kit. The longer wheelbase and new output will require new driveshafts. It was also time to replace those Dana 30 and 35 axles. Note we swapped in a Jeep TJ exhaust pipe that goes in front of the oil pan.
We ordered up a set of Currie RockJock 44 axles, the front a high pinion, the rear a low. Since this isn’t getting massive tires we went with 4.10 gears from Yukon Gear & Axle. We also had the front axle built with Dana 30-style knuckles and used a Yukon Spin-Free kit and hubs. We kept the spring-under axle suspension but upgraded to Old Man Emu 2-inch springs. We also added an add-a-leaf to the spring packs for the additional weight of the wagon body, but in hindsight we think only the rear pack needed the add-a-leaf.
The rear low-pinion Currie 44 has a Yukon Zip Locker, which is air activated, while the front has the full-time Yukon Grizzly Locker. The OME springs and shocks bolted in place after we welded the rear spring and shock perches on. We opted to weld these on at home after setting our pinion angle. The rear driveshaft from Driveline Express uses a 1310 CV joint and runs smooth as silk. We also began plumbing the fuel system with a new replacement fuel pump and fuel lines from Earl’s Plumbing.
The front Driveline Express shaft uses standard 1310 joints. Lucky for us the YJ T-case shifters attach to the side of the AX15, so it was just a matter of cutting a new hole for the shifters in the wagon floor. They are farther back than the old T-90/Spicer 18 shifters, but we got them to just clear the bench seat with the body back on. Our only regret is not swapping to a later-style bellhousing to get an external clutch slave cylinder.
Chappelle worked some old-school hot rodder magic and fixed the firewall with the metal tub of a wheelbarrow. The curved metal cleared the engine with ease and almost looks factory. The YJ’s brake booster and clutch master were all installed as we were getting close to reuniting the body and frame. The steering column was modified to use the lower portion of the TJ column so the lower steering shaft could be reused.
For wheels and tires I went with a tall, skinny 33-inch. The 255x85R16 BFGoodrich Mud Terrains came from Tire Rack, while the 16-inch Steel wheels came from Omix-ADA and were powdercoated almond-white. The wheel bolt pattern is 5-on-5 1/2, and the Currie axles were built to YJ specs but with a 5-on-5 1/2 bolt pattern and using YJ front disc and Ford Explorer rear discs.
The wiring of the YJ isn’t too bad, but oddly enough I could not find a standalone harness, so we just made the factory harness work. We only used the engine side of the firewall harness, and we deleted most of the headlight wiring because we will install a new body harness from Painless Performance. There is a wire that powers the EFI ECU and another that engages the starter. The tricky part is figuring out which is which. After a power probe, a wiring diagram, and a phone call to a few friends, we tracked them down.
We dropped the body back on the frame, bolted it in place, and built mounts for the stock bumpers. A new radiator for a YJ was installed after a little bit of bracket making, but we think it will need a custom radiator shroud. The A/C isn’t hooked up, but we have a pile of factory parts so it should not be too difficult, but it will have to wait.
The interior of the wagon has a lot of loose ends for a later date. The wiring is run to the ignition switch, but none of the lights work. We have a mechanical fuel and temp gauge, but nothing else works. The seat isn’t very comfy, and there are no seatbelts yet, so we need to remedy that asap. The steering wheel is closer to the dash than expected, so we added a steering knob for easier control. But the YJ brake and clutch pedal work great (after slight modification to clear the firewall at full engagement), and the fully custom throttle gets the 4.0L to wide open.
The Red Wagon is done for now. Sure, it has a list of little to-dos, but it runs and drives. The lockers in the Currie axles mean it can get into some trouble, but the clean retro body and lack of sliders or a winch should keep us from trying stupid obstacles. We could see some backwoods exploring looking for the perfect fishing hole in this truck, but we don’t even like fishing. So maybe we’ll just go find a cool stream and park it with an old metal cooler and a camp chair.


Currie Enterprises
Corona, CA 92880
Phoenix, AZ 85043
Painless Performance Products
Ft. Worth, TX 76105
Earl's Performance Plumbing
Bowling Green, KY 42101
Advance Adapters
Paso Robles, CA 93446
Tire Rack
South Bend, IN 46628
Suwanee, GA 30024
Madison, WI
Yukon Gear and Axle
Driveline Express

Connect With Us

Newsletter Sign Up

Subscribe to the Magazine

Browse Articles By Vehicle

See Results