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One Man's Duramax Suburban

Front Passenger Side View
Jim Allen | Writer
Posted July 8, 2004

You can't always get what you want. So you build it.

Can you tell this rig wasn't built by the factory? Visually and functionally, this is pretty much what you'd get from GM. Maybe better. Early rumors suggested that the factory Duramax rigs would be detuned versions with about 250 ponies. Not this one. It cranks out the full 300 hp and 520 lb-ft.

Many of us have been frustrated at not being able to get a particular combination of features in a new truck. It's not something that generally causes lack of sleep, hair pulling or alcoholism, but here we sit, with a pocketful of cash, waiting for a particular setup we are told will soon appear, and...nada. Well, just like the vigilantes of the Old West, sometimes a man's just got to take things into his own hands. Bill Armstrong is such a man. A farmer near Wauseon, Ohio, Armstrong has long been a fan of GM diesel-powered trucks or SUVs and has converted older GM trucks and Suburbans to diesel. When the new Duramax appeared, he was well and truly smitten, but had his heart set on a Duramax-powered Suburban. The rumor mill hinted that a Duramax-powered Sub was due soon after the pickups, but three years later, Bill was still unfulfilled.

Since leaving the sport of truck pulling, Bill has stayed busy building or rebuilding cars and trucks in his well-equipped shop. During the dog days of winter, and between farming tasks at other times, he can generally be found putting some rig together for resale or personal use. When he got to looking at the late-model GM trucks one non-farming day, he realized that it was possible, if not relatively easy, to build a Duramax-powered Sub of his own.

Looks stock to us, just like a factory Duramax Suburban would look. The best part is that all the new hop-up goodies out there could turn this Suburban into a nine-passenger rocket.

Armstrong noted that the chassis on all the 2500 and 3500 series GM trucks and SUVs were very similar within their types. The biggest differences are found in their front sections, and they revolved around things like engine mounts and such. A little detective work yielded the fact that their chassis are built in two pieces--the front, which is designed for whichever engine is selected, and the rear, which is pretty generic among the vehicle type (i.e., pickups or SUVs). The factory simply matches the front section for a type of engine with a rear section for a specific type of body to make the basic platform.

Armstrong acquired a rolling '02 Duramax 2500HD truck chassis, complete with drivetrain; a bare '02 Avalanche chassis and a complete '02 Suburban 1500 body. He put the front section of the Duramax chassis onto the Avalanche chassis and installed the Suburban body onto it. It sounds simple, but there were many small complications. Here are a few.

This is the point where the front and rear chassis sections are welded at the factory. Bill carefully unzips the pieces for his mix-and-match job. Getting them apart without damage requires some care. If you look at Bill's job and the factory job, you can't see much difference. Bill built a special jig for lining up the sections.

Because the Duramax trucks have a much higher radiator support to accommodate their honkin' big radiator and intercooler, Armstrong had to use the front wrap from a diesel pickup. This required him to use body-lift pucks to raise the Suburban body up to match, about 2 inches. Because there was a nasty gap in the rear below the cargo area doors and bumper, he had to custom build a valance to hide it. Because the body was a 1500HD rather than a 2500, there were also some minor adaptations necessary to the body mounts.



Bill Armstrong
Wauseon, OH 43567
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