The Buick GSX Stage 1 was the top of the line variant for the Buick Gran Sport. The GSX Stage 1 was a Gran Sport that was fitted with the GSX performance package, as well as the Stage 1 engine performance package. The GSX Stage 1 was offered exclusively as a two door coupe, and featured the Stage1 455 four-barrel V8 engine. The Buick GSX Stage 1 was in production until 1972.