Can somebody tell me if I have a m20 or m21? (or something else)
P9D11A then it looks like V 35008
main case casting number 3925660

The "A" suffix means it was an M 20 orginally, if it has been repaired, it could be anything now.

Originally posted by freshayr:
Can somebody tell me if I have a m20 or m21? (or something else)
P9D11A then it looks like V 35008
main case casting number 3925660 P ~ Muncie
9 ~ 1969
D11 ~ April 11
A ~ M20
3925660 ~ 1968 – 1970 1" Bore Patent Number

check your speed at 3000 rpm in hight gear. Divide the speed by 2.52 (M20 first gear ratio). Check your speed at 3000 rpms in first gear. If the result is the same you have a M20. If your speed is higher then you have the M21 or Possibly M22 gears if the transmission has been rebuilt.