Is there a way to determine what type trans I have without opening it? I want to find out either it is a M-20-21-22? Thanks. Jan
I need the casting numbers on the main case right side at the top... And the number of grooves cut into the splines of the input shaft... Crash
but in the final solution, u may have to remove the side cover to check the cut of the gears to prove an m22.
I found a number on right side top, 392566? and on the right side in rear section CCO 35959? Is this to any use? Thanks. Jan
If the casting numbers is 3925660, this case was used 1968-69 and the first part of the 1970 model year... If the casting number is 3925661, this case was used second part of the 1970 model til the end of Muncie production... The cco code is whats stamped on a Muncie main case only that bought over the counter at a GM dealership... The o at the end of the cco code stand for the 1970 model when it was put into the parts inventory... I have cases coded cc9,cc0,cc1,cc2,cc3,and cc4... The 35959 is the serial number of that case... If you had a cto that would indicate a complete trans sold over the counter... Hope this helps... Crash
On the passenger side of the main case by the center plate there should be some numbers & a letter stamped. A = M-20, B = M-21, C = M-22. This will be a good indicator. I have seen them stamped on the top. It is possible that someone changed the case therfore the only true way to tell is to remove the side cover to determine if it is a M-22.
