Need help with some transmission numbers
 

Can you guys tell me if I have an M-20 or an M-21? Here are the numbers I got off the right side of the tranny:
392566
3088336
PH3304
14S409112
Can you guys tell me what I have from these?

Re: Need help with some transmission numbers (68350hp)
 

P... MUNCIE
H.... makes no sense, this character should be the number of the production year .
third character should be a letter for build month.
4th & 5th ...... day of month
6th ...... should be
A... M 20
B... M 21
C... M 22

S409112 should be the last 7 digits of your VIN#

Recheck those numbers, I read mine wrong years ago, they are in a heck of a place for the eyes to see.