hi, i am in the middle of doing a auto to manual transmission swap in my 91firebird. i got a new trans from a salvage yard and was under the impression that it was a 5spd from a third gen but after some fitting issues(not much room to put it in and crossmember not lining up at all) and a lil ivestigation i suspect that it mite be a 6spd from a fourth gen, here are casting numbers i found on the side of the output:13-86-066-904. and here is the numbers i found on a green metal tag bolted to it:12550647 L3042
386-009 D 36817
could someone please tell me which transmission this is and if it is the 6spd(t56) are their any issues or concerns with me installing it? any information would be greatly appreciated

The numbers don't mean a whole lot to most people.

Post a pic; the difference is immediately obvious to the eye.

Yes, post a picture. It came out of a 3rd gen?

1994 (LT1) T56

Follow the T56 sticky at the top of the forum.

What did you pay if you don't mind me asking?

thankyou mike for confirming my suspicions. to everyone else after reading your replys i googled pics of both transmissions and it does indeed apear to be the t56 but if you want i can still try to post pics later. and i payed 700 for the transmission and all the other parts for putting it in (bell housing, shifter, crossmember, torque arm, clutch, flywheel, throwout bearing, release fork, clutch hydralics, peddle assembly, and shift boots)