I'm going to post a 71 Muncie M21 4 spd in the for sale section. I believe it was for a stage 1. It has the desireable 661 main case I've had this for many years and recently sold my 4spd car, so no longer need this for a spare. It looks really clean inside, but should be gone through in my opinion. It does need a bearing retainer, and also repair to the tail housing. When I purchased it years ago, we also had a rearend in the truck and it slid and put a hole in the housing. It can be easily tig welded, or swap another tailshaft housing. I'm posting this here for a week to see if it is for anyones car before I list it.