This factory information shows you how to rebuild the Muncie M20 and M21 4-speed manual transmission. Chevy dealer mechanics used this type of manual to learn new procedures. You will find illustrations of how the gears look inside the case, along with explanations of how the gears operate. See step-by-step illustrated instructions for removal, disassembly, and assembly. The instructions are presented in a slide show style where all instructions are accompanied by a black and white pictures. This booklet was written in 1963, and is also useful for 1964-1965 models. Buy now to find out how to work on your 4-speed.