How can I determine if 3 spd manual tranny from 69 GMC is Muncie, Saginaw or other?  I can read the GM numbers from the tranny but cannot determine type.  

im not real sure on a three speed but on a four speed muncie the reverse lever hooks up on the tail shaft housing . maybe same on three speed ?  

I had the same problem when I started out. I had a non-running truck and was trying to figure out if what the tranny was. The link below to the camaro.org is pretty good because it has pictures of where the the serial numbers are for Saginaw and Muncie tannys. It also has a serial decode chart to tell you what you have.

http://www.camaros.org/drivetrain.shtml#TransmissionNumbers