I just met a guy with a 05 GTO he bought from a dealership. It's a M6 with LT's no cats one chambers, fast LSX intake and some big cam, sound kinda like my MS4 and it in 6.0 motor. He's wanting to put gears in it and I haven't seen any for the GTO I'm assuming it uses the same rear as a vette right. does anybody know where I can find some.

 

Not the same as Vette. Completely differant. My best bet would go with 3.91's from Difftech. I just bought a set. Not installed yet.

 

Ditto, I think difftech is your only choice.