This is a great publication, lot of info to help ID exactly what you are looking for:
There were no muncies in 1979. The m21 rpo is for the ST10, Z28 onlyThanks, I saw that link before but it lists the muncie trans in the break down of numbers.
I am looking for specific numbers of how many t10's were produced.
Nice info. Thanks. Turns out my swap meet ST10 is from a 78 T/A. Cast 4/12/78 in Van Nuys, CA. 2.64 1st gear. Always fun to decode this stuff