I want to replace the transmission in my 1976, 350 C.I. the build sheet says that the car has a M 20 wide range transmission. I would believe that to be a muncie M 20? So, I could replace it with a M 21 short range? Is my thinking right? I just got an email from a transmission place in Florida and he says that my car has a ST10 Transmission?? What is a guy to believe? How do I find out? Are there numbers somewhere on the transmission that could once and for all tell me? Thanks....Terry spielman538402.4205208333

yeah that whole thing is rather confusing..

m-20 and m-21 were the rpo codes..

and the muncie transmissions used these part numbers..

but at some point they began using a borg warner super t-10 instead.  which i believe was based on the m-20..

are you sure you want to go with a close range though..  they are great for racing but lousy for driving

Thank you cthulhu, maybe I'll stay with the wide range. I'll assume the BW ST-10 will bolt right up with what I have now? It's all stock..Terry

im saying you may have a super t-10 like the tranny guy says..  they used the same rpo code m-20..  actually looking in the black book

the wide range four speed was offered in the base package in 1976..  the m-21 and m-40 were options

the info here seems to indicate that checvy made the switch to super t-10/m20 from muncie m20 in 75

http://www.classicsandcustoms.com/eastwood/categories/145.as p