Early Muncie Decode
 

Hello,

My Muncie 4spd on my (in transit) 69 BB Camaro has the code P9P17. From what I have read the early 69 Muncie's did not have an A,B, or C after the code. The A,B,C are what designates if they are a M20, M21, or M22. So with that said, how can I can tell if its an M20 or M21?
I am ruling out M22 because of no drain plug of course.

Thanks for the help!

Anthony

Re: Early Muncie Decode
 

Number of rings (grooves) cut into the input shaft. No grooves is a M20, one groove would be a M21. Since you also bring up M22, M22's also have no grooves, but you've already ruled that out.

Re: Early Muncie Decode
 

HMMMM - I'm used to 1969 Muncies. M22 = no grooves, M20 = 2 grooves

Re: Early Muncie Decode
 

Learn something new every day.
Thanks guys!

Can't wait to receive the car so I can take a look.....

Re: Early Muncie Decode
 

M-20's are two grooves
M-21's are single groove
M-22 are No groove
UNLESS
you come across an aftermarket input .
These also came with No groove's.
Same with Clusters
Groove's coincide with Imput's
And the factory M-20 Cluster's come with the anti-Rattle plate
riveted to the front of the Cluster.
Joe

Re: Early Muncie Decode
 

Some of the information above is correct.

1963-1965 Muncie M20 and M21 transmissions did not have any grooves either.