What year trannys work??

[kbomhower]

motor is from a 1999 gmc 2500. pretty sure its gen 3

[RedHeartbeat]

likely has iron cylinder heads, right? Any 99 and earlier 80e will bolt right to it if it has the stock flat flex plate on the engine. If you don't have a flexplate on the engine, look at the crankshaft at the back end of it and if the crank sticks out of the seal about 3/8" you just need the flat flex plate and old style 80e torque convertor.

[kbomhower]

yup it does.. i got some 243s to put onto it luckly so pretty much any year 4l80e works then. i know the crank sticks out for sure. thats one of my problems. and i have a flat flex plate. the only difference is the torque converter between the older 80es and new 80es??