http://www.dandltransmission.com/muncieratio.html may help you ID a Muncie.
http://www.dandltransmission.com/saginaw.html is for the Saginaw.
Your rear end ratio will be a factor in determining what tranny you want to use. Multiply your rear end ratio by the low gear ratio in the tranny you're looking at. If you get less than about 9.5, performance will suffer, and you'll be slipping the clutch mercilessly when taking off from a dead stop.