Part # On Muncie Trans.

[James B.]

I have a very original 67 coupe. Trans, I believe is original with vin stamping on left and manufacture date on right (P7A30). The metal GM part number tag is stamped 3890563. The only two listings I see are in the Assy manual and are 3870354 for RPO M20 and 3880853 for RPO M21 w/ L79. I have L79 w/ M20 as confirmed by the engine pad stamping, POP and tank sticker. Can anyone help me identify PN 3890563? Thanks, Jim Baker

[Joe L.]

Re: Part # On Muncie Trans.

Jim-----

There were many more PRODUCTION part numbers for Muncie 4 speed transmission assemblies than are shown in the AIM. Obviously, there were different part numbers for the 3 Muncie variants---M-20, M-21, and M-22. However, the biggest factor in the proliferation of part numbers was due to the installed speedometer drive/driven gear combination. When one factors these differences in with the 3 variants, one ends up with a lot more combinations (and, consequently, part numbers) than the few shown in the AIM.

In any event, I show that GM #3890563 was a wide ratio (M-20) Muncie used for 1967-only applications with 3.55:1 rear gears. It was never a SERVICE-available part number, though.

[Phil P.]

joe,how about 3880853 ? thanks,phil *NM*

[Joe L.]

Re: joe,how about 3880853 ? thanks,phil

PHIL-----

GM #3880853 is an M-21 used for 1966-67 Corvettes and some passenger cars with 3.70:1 and 4.11:1 rear gear ratios.

[Phil P.]

u nailed it as that is what may car has-thanks,phi *NM*

[James B.]

Re: Part # On Muncie Trans.

Joe Lucia- Thanks, My car has a 3.55 so it all fits. I didn't think about the fact that vehicle speed gear in the trans would drive different part #s based on axle ratio. Tnks for the help. Jim Baker