Like red58 said, "main cylider, typical". GM just used a picture that shows the breakdown of the parts, you'll probably find the same pic in manuals back to the '40's trucks and cars. The TF masters are the same for all years, exept for 1 1/2 ton and up and the forward controls. The 1 1/2 ton used a larger bore, the forward control models had a completly different casting. The parts breakdown is the same though.
