Muncie Transmission Seals
 

Got a 70 vette, 454, with 4 speed Muncie M20 that leaks transmission fluid. Have taken it out and apart, but not sure what seals are needed. I want to replace them all while I have it out, as well as the gaskets. Based on the #'s, the muncie was rebuilt by the previous owner from 67 and 68 parts. The good news is the gears all look in excellent shape.

If you know, please advise as to what seals I will need to buy.

This company can help you out with all your Muncie transmission parts, and questions you may have:

http://www.5speeds.com/

common place for a leak is the front coutershaft case hole. no seal there, but it wallows out and leaks. make sure it's a tight fit

There are several places who will put a steel sleeve in your case for that shaft Gary's68 is talking about.That would permanently end that leak. Trying to seal it won't last when the case hole becomes egg shape. That is a very common source of a slight leak.

The 3 shifter shaft oil seals can be gotten from NAPA...#7410...about $7 each.