I know it's a old thread, but I'm getting ready to do this to my 01 Grand Prix SE, with 107,500 on the clock.
Slightly hard shifts after a few miles. Not real hard or anything. Probably won't get to it till the spring though. I'll be happy to get 20,000 more out of the trans, as l only put a few thousand miles a year on the car.
I'll probably do the trans cooler too.
You say the one cooler the one fellow linked to on Amazon will be good for these cars?