I have a Muncie Transmission with the following info on it. Can someone tell me what I have?
Tag says 3946797, Shifter stamped "391". 2-groove coarse spline input. TH350 sized output shaft. "P0T03_CT" stamped into case ["_" is an x'd out character] Case 392566, Side Cover 3950306 , 3857584 tail with RH speedo outlet.
Can anyone help?

http://www.chevelles.com/forums/showthread.php?t=291087

I have a Muncie Transmission with the following info on it. Can someone tell me what I have?
Tag says 3946797, Shifter stamped "391". 2-groove coarse spline input. TH350 sized output shaft. "P0T03_CT" stamped into case ["_" is an x'd out character] Case 392566, Side Cover 3950306 , 3857584 tail with RH speedo outlet.
Can anyone help?

1970 muncie, December 3 is the build date. The x'd out thing is kind of wierd. It's a M20 as it is now, who knows what it was when produced.

Tag 3946797 designates M-20 1969 IMPALA, CHEVELLE, CAMARO Z28 L78

CT designates this was a "counter transmission" and not the original to your vehicle.

Thought the CT would designate Chevrolet Trans ,similar to the CE being Chevrolet Engine.