m22 how to tell from m21?

[427king]

[ QUOTE ]
On the passenger side of the main case of the trans, there should be a C-code somewhere near the v.i.n..

[/ QUOTE ] If a C case is rebuilt using m20 and m21 replacement gears ,it will appear as if its an m22 until you open it up so that is not a great indicator oif whats inside,also fine splines started in late 70 model year not 71. The easiest rule of thumb is if it has rings it isnt an M22,otherwise you need to see the gears to be sure.