jmd

iTrader: (4)

These carry the same tooth count. Why do they carry a separate part number? What am I overlooking?

There's a bevel of the gear teeth on the MN12 3rd gear at the teeth edge nearest the synchro. There are slight differences in the non-critical surfaces such as the additional groove on the non-synchro end of the gear. I don't see those as critical. Anything else I checked was within 3 or 4 thousandths height.

85MikeTPI

iTrader: (9)

Are they actually from an M12 and MM6 ? If so, you'll find the OD of the MM6 gear larger because it meshes with a different number of teeth on the MM6 countershaft.

jmd

iTrader: (4)

2006 Z06 and GTO yes.

Thanks. Will measure.