1990 Dodge Truck – Ultimate Tug-Truck: Part 5

Our Ultimate Tug-Truck is all done! But our coverage of the buildup is still going. This is the ’90 Dodge truck that started out as an airplane tug with a Cummins diesel, two-wheel drive automatic transmission, and a Dana 70 rear axle. We’ve had this beast for a while and at one point the truck lost its rear axle to another project (Clampy), and then sat derelict for years. But it has been quickly revitalized thanks to a lot of hard work by the crew at Pacific Fabrication so that it could go on Ultimate Adventure 2014.

We’ve thrown a lot of time and energy at this old iron diesel truck, and as can be seen from the photos in our Ultimate Adventure coverage, the big tank made its deadline and worked great off-road. But let’s finish up this build story so you can see more of the really cool parts in the big orange Tug-Truck. This month we’ll show you some of the gears we changed during the build, specifically when we were headed in one direction but then turned and tried something different. Even the best-laid plans can need fine tuning over the course of a project build.

In a prior installment of the buildup we mentioned trying a brand-new manual transmission called a Tremec 4050. Well, as we delved into that transmission some more, we found a few glitches that meant it wasn’t going to bolt up behind our Cummins 5.9L diesel. The people at ATS Transmission in Denver quickly had a built-to-the-hilt signature purple ATS NV-4500 five-speed for Tug-Truck. The Tremac will find its way into a Jeep in the future, but Tug-Truck needed a tried-and-true diesel transmission and the ATS five-speed is that solution.

The NV4500 is about 3⁄4 inch shorter than the Tremec 4050. The output shaft of the NV4500 is also a 29-spline and almost 1⁄4 inch larger in diameter. The Tremec is a neat design, but for a big heavy truck with Cummins torque we opted for something beefier. Plus our Advance Adapter bellhousing bolted right to it.

Between the Cummins torque and NV4500 gears we chose a South Bend clutch and flywheel. We used a ’94-style Cummins adapter to go with our Bellhousing, and we went with a single-disc organic facing clutch. South Bend offers a range of clutches with dual discs and triple discs for all types of towing and racing, but we needed a clutch we could feather and manipulate while wheeling.

Behind that ATS manual and above the custom Pacific Fab crossmember is an Offroad Design Magnum 205 transfer case setup. The Magnum has a reduction box in front of a freshly rebuilt Ford 205 transfer case to give us four gearing options: a high 1:1, a Magnum Low 2.72:1, a 205 low 2:1, and a double low 5.33:1.

TrailReady is the official bumper of UA 2014, and the company makes many great bumpers for fullsize trucks, but we were after something really high and tight. We opted to fabricate a custom square tube bumper and delete even the turn signals from our grille. The design gets optimal clearance for our tires while still housing a Warn 12,000-pound Zeon winch.

We stuffed a set of Dodge pedals in the truck to activate a hydroboost brake setup and South Bend hydraulic clutch kit. Meanwhile Jason Howerton fabricated a rollcage in the cab to protect us should Tug-Truck ever take a tumble.

Originally we had started building Tug-Truck with an AAM 111⁄2 dualie rear axle, but we finally bit the bullet and went big with a rear Dynatrac ProRock 80 axle stuffed with an ARB Air Locker and 40-spline axleshafts. This rear axle has gobs of ground clearance while still offering an 111⁄4-inch ring gear. Our rear springs are BDS 63-inch-long springs bolted to our ProRock with a set of custom FaxWorks Off-Road U-bolts.

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