[bertfam]

Peter,

ALL Muncie transmissions had a Part Number tag from the factory. Most have been lost over the years with rebuilds and what-nots, but if you still have yours, feel lucky!

The original part number for the 1968 M22 was dependant on a few things. First was when it was made. Early 68's had different part numbers than later 68's. It also depended on the rear end ratio. Here's what I have for the 1968 Model Year: (Also note that the M22 was available only on the Z28, L78 or L89 cars...)

Early 68 with 3.31 or 3.07 Posi rear end used the 3919397, which was replaced mid year with the 3932259.

Early 68 with all other ratios EXCEPT the 4.10 used the 3925626, which was replaced mid year with the 3932258. (I have no info on what M22 was used on the 4.10 and why it was different. Sorry...)

I'm not sure of the exact dates of the part number changes, but I believe it was in early 68.

Hope this helps...

Ed