Chevy BIG kid

Hi there, I was hoping someone might have some insight into what year vehicle this T56 transmission came out of, I know it is an LT transmission from the pics, however I was told to stay away from the 93 LT T56, and there is a LT t56 on Craigslist for 900 but the only markings on it are 13-86-066-904 on the tailshaft and 13-86-065-902 on the main case. The white sticker has decayed beyond legibility. I do not see any tag, however I have only seen pics. I have been searching the web all day and have been unsucessful, I would appreciate any help from anyone that knows more than I. Thanks

calhoon

iTrader: (6)

Those are casting numbers and don't help as all Fcars had those. You need the tag info.

jmd

iTrader: (4)

put it in 1st gear.
Spin the output exactly 3 times.
If the input spins 10 times, it's 1993 M28 (2.73 rear gear, 3.36 first gear)
If the input spins 9 times, it's 1993 M29 (3.23 rear gear, 2.97 first gear)
If the input spins 8 times, it's 1994 MM6 (3.42 rear gear, 2.66 first gear)