How do you identify an M-22. Seems to me it had to do with the splines?

 

http://www.5speeds.com/muncie2.htm

 

If you do not know the absolute history of the tranny, then the ONLY way, repeat, ONLY way to distinguish an M22 from an M20 or M21 is to remove the side cover and look at the angle of the gear teeth. Nowhere Man has posted a web site that illustrates the difference in teeth angles (on page 3). If you looked at the pictures, you saw that the M22 teeth angle is less than the M20-M21.
In 1969, the stamped date code included an A, B, C at the end of the date code which corrosponded to M20, M21, M22. BUUUUUUUUUUT, if for whatever reason in its past the tranny had to be rebuilt or have a gear replaced, then the M22 gears could be gone from an M22 case (you CANNOT replace ANY M22 gear with an M20 or M21 gear).
Also, you CANNOT distinguish an M22 simply by the splines. ALLLLLLLLLLLLLLLLLLLLL 65-69 M22s had the 10 spline input/27 spline tail shaft just like a regular Muncie. The later production 70 M22s had the 26 spline input/32 spline tail shaft. ALLLLLLLLLLLLLLLLLLLLLLL 71-74 Muncies had the 26 spline input/32 spline tail shaft.
The PRODUCTION M20 Muncies had had 2 grooves (66-74) around the input splines and ALL M21 Muncies had one groove. The M22s had NO grooves at all and the 63-65 M-20s also had no groove. Now, if a M20 or M21 had its input replaced, there may not be any grooves at all either because most replacement inputs did not have grooves around the splines.
So, that brings us right back to statement number first. If you do not know the absolute history of a Muncie (that is supposed to be an M22) the ONLY way to tell is to remove the side cover and look at the gear teeth angle. PERIOD!

 

M20 and M21 gear helix angles look like this:



M22 gear helix angles look like this:

 

Thanks! I'll be checking out the Barn Find car for this Trans.