From Chevy Wiki
The Chevrolet Titan 90 (and similar GMC (General Motors division) Astro 95) were Heavy-duty Class 8 Cabover Truck made by General Motors between 1968 and 1988. When introduced, they replaced the GMC F-Series "Crackerbox" & featured an all-aluminum tilt-cab. Diesel engine choices included Caterpillar Inc., Cummins and Detroit Diesel powerplants.
In 1980, both trucks were redesigned with a bigger grill.
The GMC version was more common than the Chevrolet version.