So I've rewired and tuned my LS6/4L80E for my own car. A friend of mine now wants me to do his harness and programming on his LS conversion. He bought an LS3 out of a 2008 corvette and a 4L65E. He bought the AP from the same vette. His ECM is Serv# 12612384.

I think I'm in over my head. All the research and reading I've done hasn't led me to which TCM Serv# to buy that will work with his ECM. Or which OS I can start with that'll run the LS3/4L65E.

Can someone point me in the right direction?