muncie trans.

[will]

does anyone know how to tell a m20,m21 or m22 with out tearing it apart? ,it is out of the car.

[Allen]

Hi! I'm new to posting on this board, but have enjoyed reading it over the past few months.

Regarding your Muncie question, I believe that there are a couple of ways to determine whether or not you have an M20, M21, or M22.

I don't know what year GM started doing this, but after the date code on the side of the case there might be a letter A, B, or C. This letter indicates which it is. A=M20; B=M21, C=M22.

Another method might be to count the grooves on the input shaft.
Two grooves = M20; One groove = M21, Zero Grooves = M22.

I might be wrong, or backwards in my assumptions for what the groove or letter equates to. If so, I apologize, and I'm sure another person will steer us both in the right direction.

Good luck!

[bowtie3168]

I think that your info might be correct but, if you want to check codes you should check out the info in Allen Colvin's books called "Chevrolet By The Numbers".

Andrew

[will]

I'll have to look ,but I think I have that book . where do find the numbers on the trans ?
will

[JoeC]

Since Muncie parts can be interchanged during a rebuild the numbers may not tell you which trans it is. The best way to see what you have is to open the case and count the teeth on the input shaft gear.
M20 will have 24 teeth (less on some models)
M21 has 26 teeth on about a 45 deg angle
M22 also has 26 teeth but will have almost straight cut teeth (about 20 deg. angle)
here are two web sites with alot of Muncie info
http://www.corvettemagazine.com/proofing/muncie1/munciep4.asp

http://www.5speeds.com/muncie.htm

[rbernat]

trans.id prefixes appeared on the case in 1969.but of course the internals may have been changed.

[will]

Thanks ! I supose I'll just have to open it up
will