Hy 1950firetruck, your engine is a 248 GMC, for some reason Canadian 248s were not identified the way their American cousin engines were with the C.I.D. as the first three digits of the engine number, but rather the letter G was the first digit of the engine number. Is your truck equipped with a single speed or two speed rear axle? Your transmission is an SM420, and your truck has five bolt Motor Wheels, hope that helps.
