1990 Dodge Truck – Ultimate Tug-Truck: Part 2

The Ultimate Adventure is a fun trip, like summer camp for off-road guys, and we are the counselors. We lead our troop of off-road fanatics on a weeklong escapade as we wheel and road-trip down backroads and over extreme trails. The vehicles we take must be well rounded, big enough for gear and camping supplies, but small enough to fit between rocks and trees. They must be capable of highway speeds and slimy off-camber trails while laughing off body damage. These vehicles are part MacGyver, part Survivorman with a little of grandma’s comfort thrown in since we’ll be living with them for a week with countless hours of driving. As our official ride for the 2014 UA, we are building a ’90 Dodge truck that started as a two-wheel-drive airplane tug.

We introduced our Tug-Truck last month, and now it is at Pacific Fabrication in Gilroy, California, getting stripped and ripped into a big yet nimble diesel wheeling machine. Simplicity yet strength is the name of the game on this build. The Cummins engine can run on three wires, so we’re not going to go overboard with a computer-controlled transmission or too much extra whiz-bang. The plan is simple and stupid-proof, since we know who will be driving it –us!

The Tug-Truck is getting almost everything deleted save the reliable Cummins engine. This truck earned its stripes dragging airplanes around with gobs of low gears, so although the diesel is broken in it is not worn out. Civilian life will not be all relaxation by the pool though. We’re expecting 40-inch Nittos and some anvil-tough components between them and the Cummins.

This month we are stripping it to the rails and forming a plan for monster build Dr. Frankenstein would be proud of.

1. All of the front two-wheel-drive suspension needs to go from our Tug-Truck. However, we did notice that the steering box does turn in the correct direction for a solid front axle. We’ll keep that for now.

2. Whenever anything we didn’t want on the front suspension couldn’t be unbolted, the Pacific Fabrication team devoured it with plasma cutters. A large front suspension crossmember under the engine ties both framerails together.

3. The crossmember was torched down to just a slab running from side to side to help hold the frame square under the big Cummins while we determine where the front axle will sit. We will either reuse what is left or cut it out completely and build a new crossmember once we place the front axle and suspension.

4. Behind the 5.9 Cummins there is a two-wheel-drive TorqueFlite 727 three-speed automatic transmission. Though that is a very robust transmission, we decided that a manual transmission is a better option for this truck since simplicity is the goal.

5. On the back of the Cummins is an adapter plate that the bellhousing bolts to. Various bolt pattern adapter plates are available for the Cummins depending on the year and model of transmission. There are even adapter plates to put a GM transmission behind the Cummins if need be. Behind the engine we removed all the crossmembers and cleaned the C-channel frame for ease of fabrication for our new drivetrain.

6. Once the truck was deleted of everything unimportant it was time to begin putting it back together. Pac Fab started by attaching the bed to the frame with weld-on mounts. The bed was mounted up slightly off the frame two inches to help add space for our fuel system and align with body lines on the cab, plus this helps in ground clearance between the bed and trail obstacles. The steel surplus military trailer box will bolt directly to the frame mounts and add substantial rigidity to the fabricated C-channel frame.

7. Once the bed was attached we began mocking up our new Jaz Fuel cell. This fuel cell is 32-gallon bladdered tank that has a raked rear departure and is designed for use in a Jeep XJ for JeepSpeed desert racing. We ordered it with a 45-degree filler neck but had to modify it for an even lower fill since the fill point is right up under the bed.

8. The Jaz cell has an internal bladder and a metal case, but we also had a skidplate mount made to doubly protect it for when we drop the tail of the truck off an obstacle.

9. Currently we are not 100 percent sure on our rear axle. We have a used massive AAM 111⁄2-inch dualie rear axle from a late-model Ram 3500, but we are considering upgrading to something with better ground clearance. We do, however, plan on leaf springs in the rear and started by mocking up with some junkyard Chevy 63-inch-long leaf springs from a late-model truck. By starting with stock leaves we can easily upgrade to any size lift spring based on the ride height we start with.

10. We are mimicking our old Dodge M37 build (“The Dumpster,” part 3, Sept. ’10) and using an Offroad Design shackle flip kit to hang the leaf springs and then use the shackle in the rear in a tension design. This keeps our springs slanted, with the rear higher than the front, and helps with the suspension geometry.

11. Next issue we will swing the front Dynatrac ProRock 80 axle under the Cummins to get an idea of just how tall our Ultimate Tug-Truck will stand. Return in 30 days to see part three of our build.

Ultimate Adventure 2014 Sponsors

BDS Suspension



Official Suspension

Method Wheels



Official Wheels

Nitto Tire


Official Tire

Offroad Design



Official Transfer Case

Pacific Fabrication



Official Fabricator

Power Products Unlimited Inc.



Official Retailer

VooDoo Off-Road



Official Tow Rope

Warn Industries Inc.



Official Winch

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