the gt's came with the 4t-65e trans, the gtp's came with the 4t-65eHD trans. the latter has a 2.93 final drive ratio, while the first comes with a 3.29 ratio. the HD model also has a stronger internal part, the name of which i forget at the moment. if i were doing a swap for speed, i'd keep the 3.29. if i were doing it for dependability, go with the fresher one.
for what it's worth, my engine has 148k miles and runs stronger than a lot of other cars ive driven. you gotta think, if your car is worth 2k, and you put a 2700 motor/trans in it, you're asking 5k for it to make any money. there aren't many people that would pay 5k for a grand prix anymore. i'd clean it up really nice, replace anything that's worn out, and throw a $2700 sign on it and let somebody talk you down lol
