sentences:  After 1981, the Chevrolet Bison was discontinued, following the withdrawal of Chevrolet heavy-truck production.In 1986, General Motors entered a joint venture with Volvo to produce heavy trucks, leading GMC to end production of the General conventional and Astro cabover in 1987.As of 2020 production, the 1987 GMC General and Brigadier are the final Class 8 conventional-cab trucks produced by General Motors.