Based on bcmiller's post below, were different PN's used on Muncies based on the *rear end ratio*?? Why would they do that??
(I'm trying to learn my 'Camaro new information for the day'...
Because each different rear end ratio required a different plastic (I think) gear to make the speedometer read correctly.
Actually, the plastic DRIVEN gear was installed at the car assembly plant. What changed was the internal steel DRIVE gear that was pressed on the output shaft at Muncie;
Actually not pressed on, the gear slips over the tail end of the mainshaft and is secured by a spring steel clip. How do I know ? My '69 Z M20 clip broke, lodged in the reverse gear, and jammed the transmission. I made it to the station I worked at, pulled the trans and found the problem. New clip and back in business. Earlier Muncies pressed on -