sentences:  Along with single or tandem axle configurations, the GMC "Crackerbox" was available with a sleeper cab.In the late 1960s, as American truck manufacturers introduced updated designs for cabover trucks, design work began on an all-new Class 8 cabover.Expanding the product line to the Chevrolet brand, the replacement for the GMC Crackerbox sought to expand interior space, visibility, and driver ergonomics.