Chadborne

The transmission that came with my 1970 454 has several numbers on it, but I can not find M20, M21 or M22 on it. Where is it located?

Also, the number above the GM U.S. patent number is 3885010 which I understand is the casting number for 1965-1967. Is this true? The person that sold me the car was not the original owner, but he thought it was all original.

Other numbers that are stamped in the transmission are 3884685 and 3846429. Any idea what these are?

dannyman

This link will address most of your questions,

http://www.5speeds.com/video.html



3884685 side cover

3846429 tail housing

dmayhew

There ia a number stamped in front of your cars VIN # stamp on the transmission case that wil end with a A / B / or a C

A= M20

B=M21

C=M22


David

FrankVincent

3885010 = Maincase number for 1966-67 ... M20, M21 or M22.

3884685 = Sidecover number for 1966-67-68 ... M20, M21 or M22.

3846429 = Tailhousing number for 1964-65(until Feb '65) ... M20, M21 or 1965 ... M22.

There is a build date on the passenger side of the rear maincase, reading in a vertical position. That will help determine a specific manufacturing date. There will be no A,B or C suffix code, as that started with the 1969 model year. Otherwise, it sounds like you have a transmission using various parts, and the only way to tell what you actually have is to open the sidecase and count teeth.

- - - - - - - - - - - - -

P7B01 = Build date = 4 speed Muncie, 1967, February 1st

GFehlman

I have a M20 out of my 68 Vette, I know the main case numbers and the tail piece, but what does the 3915088 that is on a tab bolted to the side cover stand for?

Red Vert 02

From checking around the internet I found 3915088 is a 1968 Muncie M20.