Possible, sure, but why would you want to? The conversion parts are going to cost you a pretty penny and the T5 isn't anywhere near as tough as the TR3650 that replaced it.
You're better off shopping around for a used TR3650 than you are trying to make a T5 work in it's place.
Just wondering if was possible,I'm not gonna do I was just settling a argument ya know what I mean,but I do have a 2004 gt and the second gear sincs are bad can u buy a rebuild for the 3650 or is simpler to just find another trans?