A direct replacement 8.8 will be 99-04. It does not matter if the GT was auto or manual.

 

+1 but some 99/00 auto GTs had 3.08 gears, which you will just have to reflash the computer

 

I'm still trying to figure out how his rear end is in need of any service at all

 

^+1, we need the whole story

 

well the car was making a noise in the back wheels when i bought the car, i took it to the mechanic but they did not found anything, but i knew there was something wrong. Over time the car was making the noise more often and its really loud. I took it to the mechanic again and they told me that the part in the center of the axle was damage(the center where the gears are)

 

But that's just it, that part doesn't break, it doesn't even wear out. It can't even be checked without draining all the rear end fluid. Get a better mechanic

 

Maybe his spider gears went? or pinion gear?

 

Yeah but that isn't the diff, those are all seperate. Spider gears go in the diff, and ring gears are bolted to the diff. A differential is just a case that holds the spiders and ring gear and sits between the shims and bearings. They don't wear out. If something is broken, then they would have still had to open the cover to see what it was. If it's a pinion seal, then that's just about and hours work, seal and fluid.

R&P's don't really wear out too often either. They're either messed up from the start or last 400k+

 

yea it was something to do with the gears, but i just wanted to change the whole thing cause it would be almost the same price.

 

whatever, good luck, and let more **** mechanics sell you stuff that doesn't exist or doesn't go bad. Just don't buy the gold plated muffler bearings, standard polished stainless will do fine.