Hello, all. I am a mechanic in St Pete, Florida, and I have a customer with a 1997 Vette, having some automatic transmission problems, 3rd gear is going out and he wants me to replace the unit. He has a 1997 with a "7YDD" designation, and he has a source on a 1999 unit that has a "9YDD" designation, and the only thing I can find on them difference (other than the code) is that the earlier one is a VIN P and the new one would be from a VIN G. Supposedly they're the same from 1997-2004, but I would hate to get the job halfway done and find out it's not quite right. Any help would be greatly appreciated. Thanks.