Transmission Identification, M-21 or M-22 ?

[Jacob A.]

Hello,

I just scribbled down the #'s on the tranny of my 69.

Here are the #'s:

The raised or cast # that goes from side to side, I guess this would be the Casting # is 392566. The stamped #’s that read up and down on the narrow flange is or appears to be P9R234 the last digit is either 4 or A. What do you make of all that?

Tranny has two holes for the fluid. One to check, and one to drain. I didn't see the car's vin or even part of it in any of the #'s on the transmission. It sure whines unless your foot is depressing the clutch.

Thanks,
Jacob
NCRS # 40987

[William C.]

Re: Transmission Identification, M-21 or M-22 ?

what size is the output shaft? BTW the casting number has the last number missing, Either a "0" or "1" making the last series 660 or 661. All the 661 cases had the lower drain so nothing is learned from that, but the 660 case only used the lower plug on the M-22. if the last letter is an "A" on the stamped code, then the trans was originally an M-20 wide ratio trans, although gears could have been swapped, but an original '69 "Rock Crusher" would carry a "C" code as the last character in the stamped set P-----C

[Jacob A.]

Re: Transmission Identification, M-21 or M-22 ?

Thanks Bill, I will have to check the output shaft, but I think maybe there was a 1 at the end of the casting #, I just thought it might have been a stamp from the tool that held the #'s .

It there was no 4 offered as the last letter on the stamped code... then I would have to guess that is is a A, and that the tranny is a M-20. Hmmm? Sure does whine, like nothing else I have ever driven.

I wonder.

Thanks again.
Jacob

[William C.]

Re: Transmission Identification, M-21 or M-22 ?

If the gearset has been changed, pull the side cover and look inside, the helix angle of the M-22 Gearset is quite pronounced in it's difference from the standard gearset. It would help if you had a std gear with you for comparision.

[John H.]

Re: Transmission Identification, M-21 or M-22 ?

Pull the side cover (put it in 2nd gear first), and if the gears look like this, it's an M-22 (about a 20* helix angle). The link below will show an M20/21 gearset (about a 40* helix angle).

[Jacob A.]

Re: Transmission Identification, M-21 or M-22 ?

Thanks an impressive reply!

Thanks a bunch,
Best Regards.
Jacob Angel