I can attest to this //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif.. In my 1999 Grand Prix GT (same drive train w/out a SC), I went through an engine and a transmission. My buddy with a 1998 Grand Prix GT, same as mine, but red, and a year older, went through two transmissions.
The sad thing is, mine was never driven hard. It was babied all the time. I wish I could say the same for my friends car, he beat the shit out of the thing.
I would say that they are pretty reliable, as I am looking into getting a GTP //content.invisioncic.com/y282845/emoticons/yumyum.gif.0556df42231b304b9c995aefd13928a8.gif
Stay away from auction vehicles, as that is where I got mine at... //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif