The story of Jim Williams’ incredible 1974 Ford C-750 custom 4×4 motorhome began in a salvage yard in Canada. “We were there looking for parts for my buddy’s truck, and I got about a hundred feet into the scrapyard, saw this, and it was like, ‘Yeah, OK, this can’t stay here—it’s gotta come home with me.’”

What Jim saw was an ex-U.S. Air Force crash truck, and it became the foundation for his motorhome. It took three years to transform the truck into what you see here, and another six months to repower it. We found the truck on display at the 2025 38th Annual Steve Shannon Summer 4-Wheel Jamboree in Bloomsburg, Pennsylvania.

460 Cubic-Inch V8

Jim says the Ford was originally based at Plattsburgh Air Force Base in New York. After the base closed in 1995, the truck was sold off and it eventually made its way to Canada. Originally, the truck was fitted with a 391 cubic-inch engine and an Allison transmission. He says the transmission gave out after about 1.5 miles of driving, and this was the catalyst for a complete repower.

Jim replaced the stock engine with a modified 460-cubic-inch V8 that produces around 400 horsepower. It’s mated to a custom Lentech C6 transmission. Fitting this duo into the truck required Jim to design and fabricate engine and transmission crossmembers, radiator mounts, throttle linkage, power steering pump mounts, and more. The engine is fed by a 65-gallon fuel tank.

Power is sent to the factory divorced Dana Spicer transfer case, where it’s routed to the truck’s factory axles. They are equipped with Eaton Detroit Lockers and 7.17:1 gears. The front axle is fitted with manual locking hubs, which were not standard on the truck. Jim says it took 10 years to find the hubs, and he had to travel to New Jersey and purchase a complete axle to acquire them. The truck retains its leaf-spring suspension.

The truck rolls on its original steel wheels, and they’re fitted with 425/65R22.5 (44-inch-diameter) Goodyear G278 MSD radial commercial tires.

Owner-Designed-And-Built RV Body

Replacing the factory crash truck body is an RV body that Jim designed and built. It’s equipped with everything you’d expect for self-sufficiency in the backcountry, including indoor and outdoor showers, a toilet, refrigerator, and stove. Additionally, it has hot and cold running water, a furnace, air conditioning, and a massive generator.

The interior includes custom woodwork and a ceiling inlay. The plank door to the bathroom has a half-moon cutout, there’s a tree trunk at the rear of the RV that serves as a ladder to access the roof hatch, and the bedding and curtains are made from material acquired from Cabela’s. The RV has a 30-gallon freshwater tank, a 40-gallon black water tank, and 50-amp electrical service.

More Details

Jim spent a vast amount of time hunting for and acquiring parts for the rare truck. For example, the chrome outside rearview mirrors were sourced from a junkyard in Indianapolis, Indiana, and came off a garbage truck. The chrome grille is from a junkyard in Ohio, and the entry door on the RV—found in New York State—is from an ambulance. The mud flaps came from Australia.

Other exterior features include the stock front bumper with custom tube work, custom rear bumper with an adjustable-height hitch receiver, and custom wrap.

We’ll end with numbers: The truck’s total length is 26 feet, and it weighs just shy of 18,000 pounds. The RV body is 16.5 feet in length, plus the 7-foot over-cab extension. Like its license plate says, it’s a big ‘ol truck.