Does anyone know how to find out what a part is by the part no.? I have books that list casting no. but not part no.
I'm trying to find what part no. 3946797 is. I think it is a 4sp trans and I would like to know if it is a M21 or M20. Thanks

I show this is a 1969 Muncie 4-sp with 2.52:1
first gear. That should be a M20.
The 1969 M21 has part #3946798 with 2.2o:1 ratio.Found the listings in MSA-1 Chevelle book.

RENE
66-Malibu

Thanks Rene My book lists the 3946798 as the M21 like you said and the M22 as 3950318 but I could not find the 3946797

While we are on subject of Muncies, I have a Muncie with the following code stamped on the side that I scored for a really good price of $425 with a new Hayes clutch and flywheel. I believe it is a '67 M-20 has Vin number 7K120384. Numbers on pass side main case are 3885010 P7AO6. An apparently once replaced tailshaft with the numbers 3846429 and vin 7L128699 tailshaft. Gear selectors seem to have been replaced with newer non-stud shift selectors.

The P7A06 is a Jan.6 1967 date. If it has one ring on the input shaft it's M21, two rings M20, no rings is a M22. To verify this you need to count the teeth on the input shaft gear inside the case. 21 teeth=M20, 26 teeth M21 and M22 but the M22 will have less of an angle cut on the teeth (more of a straight cut)