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Muncie 4-Speed Transmission Year?/M22?

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Old 10-18-2008, 05:56 PM   #1
Chadborne
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Default Muncie 4-Speed Transmission Year?/M22?

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?

Last edited by Chadborne; 10-18-2008 at 06:00 PM. Reason: Forgot to include that the number P7B01 is stamped in the transmission.
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Old 10-18-2008, 06:57 PM   #2
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This link will address most of your questions,

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



3884685 side cover

3846429 tail housing

Last edited by dannyman; 10-18-2008 at 07:01 PM.
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Old 10-18-2008, 07:15 PM   #3
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Quote:
Originally Posted by Chadborne View Post
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?
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


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Old 10-18-2008, 11:16 PM   #4
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Quote:
Originally Posted by Chadborne View Post
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?
Other numbers that are stamped in the transmission are 3884685 and 3846429. Any idea what these are?
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

Last edited by FrankVincent; 10-18-2008 at 11:19 PM.
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Old 11-14-2017, 05:41 PM   #5
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Default Muncie M20

Quote:
Originally Posted by Chadborne View Post
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?
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?
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Old 11-14-2017, 09:44 PM   #6
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Originally Posted by GFehlman View Post
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?
From checking around the internet I found 3915088 is a 1968 Muncie M20.
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