By Ron Covell – Images Courtesy of Roadster Shop
The GM OBS trucks from 1988-98 are enormously popular, and most builders want to lower them—sometimes dramatically. Air suspension systems are a common choice for this application, since they can allow the chassis to drop all the way to the pavement when parked, then raise quickly to any desired ride height with a simple in-cab control.
If you attempt this with a stock frame and suspension, you’ll run into countless obstacles. Most often, the bed floor must be raised substantially, and in some cases, even the cab floor requires modification.
Roadster Shop carefully analyzed these issues. By scanning the entire body and chassis, they were able to CAD design a completely new chassis with fully independent suspension that fits this truck. The result is a setup that allows a full body drop without the need to alter the cab or bed floor.
Jon Hall, owner of Shadow Rods, owned a 1990 GMC Stepside in decent cosmetic condition, that he wanted transformed with Roadster Shop’s new LowPro chassis. In the following pages, we’ll walk through the process—and you’ll see that it was far more straightforward than in many builds of this type.
Once the cab and bed were removed from the old chassis, a new firewall was fabricated. Filling every hole and recess in the stock firewall would have been a monumental job, so the crew opted for a smarter approach; they covered it with a flat plate of heavy-gauge sheetmetal. This produced an exceptionally clean look. It is consistent with the build’s theme, and it saved a considerable amount of time.
New front wheelwells were required to clear the suspension’s full drop. These were fabricated from 16-gauge steel. Instead of complex, highly contoured panels, the crew built them from flat and single-curved sections that perfectly suit the clean, functional style of the build. These panels are now available as a product from Roadster Shop.
Large plain surfaces can sometimes look a little too stark, so the team added subtle but stylish details to a custom panel that caps the radiator and core support. It’s not flashy, but the tasteful accents provide a spark of visual interest when the hood is opened.
In the rear, new inner wheelwells were fabricated to clear the wide wheels and tires. These were neatly joined to the inner bed panels, resulting in a factory-like look.
Roadster Shop also built a complete stainless exhaust system. Thanks to the thoughtful chassis design, there is ample clearance even for large-diameter tubing—up to 3-inch diameter.
One huge advantage on this particular project was the outstanding condition of the truck’s original paint- and bodywork. Only minor touch-ups and careful polishing were needed to restore a show-quality finish.
As you’ll see in the photos, relatively little fabrication was required to complete this striking build. That’s a direct result of the extensive engineering that went into the chassis design.
Check out this story in our digital edition here.
