m21 trans

[Mike S.]

i have a 71 454 car, on the trans # c11s111144 .i think its a m21 .also 392566 i think this a cast #. tank sheet says close ratio . but cant read whats in front of close ratio.

[Joe L.]

Re: m21 trans

Mike----

There will be a transmission production code located on the same surface that you found the VIN derivative. It will be an alpha-numeric code beginning with a "P". The last character of the series will be an "A", "B", or "C". If it's an "A", it's an M-20. If it's a "B", it's an M-21. If it's a "C" (unlikley), it's an M-22.