Aerodynamic enhancements

In stark contrast to the boxy Crackerbox, the exterior of the Astro/Titan featured rounded body corners and wraparound windshield glass.^[4] In 1975, GMC introduced a Dragfoiler roof spoiler as an option.^[4] In an option that became standard a year later, in 1979, GMC and Chevrolet offered the SS (Special Series) package.^[4] Featuring a (much) larger radiator grille, improvements to exterior and interior trim, the SS package was meant to market the Astro/Titan towards owner-operators.^[4] In 1983, the Aero Astro option package was released, largely as an effort to improve fuel economy. Along with the Dragfoiler roof spoiler, the option package included body extension panels between the cab and trailer, an air dam below an extended bumper and an optimized radiator grille.^[4]

Powertrain details

In a major change from precedent, when introduced in 1969, the Astro/Titan were marketed exclusively with diesel engines. The base engine was the Detroit Diesel 6-71N, with the Detroit 8V71 and Cummins N-Series diesel engines as options.^[4] In 1972, the Detroit 12V71 became available as an option; though rarely ordered, the V12 engine would remain through 1978.^[4] Although Detroit Diesel had developed a gas-turbine version of the GMC Astro in the early 1970s, fuel-economy concerns would keep it out of production.^[4] In 1977, the Cummins KT450 and Caterpillar 3406 became options; the larger engines required the addition of a larger radiator.^[4] In 1979, the 6-71 was replaced by the 6V92, making all available Detroit Diesel engines V-engines; the 6V71 was discontinued after 1980.^[4]

Chevrolet division withdrawal

In 1981, General Motors ended sales of heavy trucks by the Chevrolet Division, leading to the cancellation of the Chevrolet Bruin, Bison, and Titan. A major factor leading to the cancellation was lack of support for heavy-duty trucks by Chevrolet dealers. In contrast to other GM brands, a key requirement of GMC franchisees of the time was the ability to sell and service the entire GMC product line. In addition to light trucks, this meant a potential GMC franchise needed the ability to support medium-duty trucks, heavy-duty commercial trucks, the GMC motorhome, P-chassis, and school bus chassis. For a typical dealership, this meant dedicating profitable space that would have otherwise gone to selling passenger cars.

Volvo GM venture

In 1986, Volvo AB entered into a joint venture with General Motors in heavy-truck production, with Volvo taking an 85% stake. Having already acquired White Motor Company in 1980, the joint venture would do business as Volvo GM Heavy Truck Corporation, selling trucks under the combined WhiteGMC product badge. Under the joint venture, GMC trucks were phased out in favor of White-designed Volvo GM products. The GMC Astro ceased production after the 1987 model year (coincidentally, two years after Chevrolet launched a van with the same name).

Although Volvo GM would continue sales of COE trucks under the White GMC and Western Star brands (the WhiteGMC WH and Western Star Cabover; both versions of the White Road Commander II), the GMC Astro was never directly replaced by Volvo GM, Volvo, or General Motors.