This Chevy Silverado “Squarebody” Crew Cab Dually was a workhorse at GM facilities in California, Arizona and Michigan. After years of service, it was headed for the scrapyard when Chevrolet Performance engineers seized it for use as test vehicle for the ZZ632/1000 crate engine — the largest and most powerful crate engine ever from Chevrolet.

The Chevrolet Performance ZZ632/1000 is the ultimate crate engine from Chevrolet. It is rated at 1,004 horsepower on premium, 93-octane pump gas, with highlights including a tall-deck block, all-forged rotating assembly, racing-inspired RS-X spread-port cylinder heads, crank-trigger ignition with individual coils and electronically controlled fuel injection.

The cab’s interior was left largely untouched, except for several replacement gauges that monitor the engine and 4L85-E four-speed automatic transmission. There’s also an interface module for the electronic fuel injection system’s self-learning control module, which is included with the crate engine package.

After spending most of its life at GM facilities in the Southwest, the Development Dually’s original red finish has developed a timeworn patina. The only external clue to the truck’s high-performance engine upgrade is a cowl-induction-style hood scoop that provides clearance for the ZZ632’s high-rise intake manifold, throttle body and air cleaner.

Several of the replacement gauges are designed to work with the electronic signals from the engine and transmission controllers. It’s a requirement for many Chevrolet Performance crate engines featuring production-style fuel injection systems, including LS and LT crate engines.