Muncie Side Covers

[baldeaglemtnman]

I have an M-21 with an assembly stamp of P8H08 and and an M-22 dated P8R30. Both have 660 main cases and a 584 tailshaft housings. The M-21 has a 3952648 side cover and the M-22 has a 3884685.  Are either of these correct?  If not, what is?  When were the 306 side covers introduced?

[bertfam]

Steve, the 3884685 is correct for your M22 and would also be correct for your M21. The 3952648 was introduced for the 1970 model year and the 3950306 was introduced for the 1969 model year.

Ed

[baldeaglemtnman]

Thanks for the quick answer Ed. That's what I needed to know.
 

[JohnZ]

The 648 side cover introduced for 1970 has a threaded boss adjacent to the 3-4 shift fork boss for the TCS switch.