Is it an M21 or an M22?
Look here. Gears are cut straighter for more strength, output shaft is larger, etc.....
Mickey is correct. Look at the link Mickey attached. The M21 and M22 had the same 2.20:1 first gears. The M22 used a stronger alloy steel and had a straighter helix angle on the main gear set, as is shown in the pictures on Mickey's link.
The helix gear angle is 39 degrees on the M21's and the M22's have a helix gear angle of 21 degrees as shown in the pictures from the link.
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5 months ago
My 4 speed Muncie tranny has a 2.20 1st gear. so that mean it's a close ratio tranny. Are there any physical differences between the 2 transmissions? Extra webbing support on the tail, wider ears, etc?