Hey, Jim, thanks for the link - great info there. Based on what I read, the casting number is from an M20, M21, or M22 from 1968-1970, so it could be the original trans.
And it sure feels like a close ratio trans - not much of a drop in rpm b/w shifts - so that would narrow it down to an M21 or M22 - but it appears that there is no way to tell difference b/w M21 and M22 without taking it apart (angle of gears is different) unless you can hear distinct gear whine while driving. Well, I have a huge gear whine, but it's coming from under the hood - am about 99% sure that my engine has a gear drive - it's LOUD!
So, some of the mystery is solved, but not all of it...
