The Chevrolet Bruin (and similar GMC Brigadier) were heavy-duty trucks made by General Motors since 1978. The Bruin & Brigadier were both conventional rigs using the 9500 series cab introduced in 1966; this cab was better-finished and more stylized than a typical big-rig cab, but larger than the pickup-based cab used on the contemporary C50-C70 series. It had short 92.75″ BBC.
Diesel engine choices included Caterpillar 3208 164 and 199 hp, Cummins NTC-250, Power Torque 270, NTC-290, NTC-350, Formula 290 and 350; and Detroit Diesel series 53, 71 and 92 powerplants. The hood tilted forward a full 90 degrees for easy servicing.
In 1979 series nomenclature had been changed. H70, J70, H80 and J80 trucks all became J80 Series trucks. H90 and J90 trucks became J90 Series trucks. Some models had a hood from the old Series 70 / 80 trucks.
For some reason, the GMC version was more common than the Chevrolet version. This was probably because for many years, in order to have a GMC franchise; the dealer had to carry light trucks, medium trucks, heavy trucks, and service the school bus chassis, and the P-chassis all under one roof at the same location; while most Chevrolet dealers dealt only in passenger cars and light trucks (up to 3500 series).