My car had an M21 when I bought it in 2000. In 2004 I pulled it out because it wouldn't stay in 4th gear (kept popping out). When I pulled it, my buddy game me what I thought was a T-10 and it's been in there ever since. It has a REALLY low first gear.
Today I went to a friends house and we looked it over, as I now have a brand new M21 blue printed and ready to go in the car. I had a buyer for the T-10. As it turns out, I have a Saginaw 4 speed and not a T-10. The guy was suprized that I have been running it for the last 4 years especially the way I like to beat my car (when it runs right) that is.
Anyway, that Saginaw doesn't seem to be too bad IMO. Although I am looking forward to getting the new M21 back in the car...