needcheese

I have an 08 base coupe with 4.10 gears along with other mods. I would find a speed shop that will sell,install the third member/differential, and use your old one as a core charge. It is better to get one that has already been built and ready to go. I would also get upgraded half shafts at the same time. I did lose a few MPG on the highway but the city driving all depends on the use of your right foot.

Crowhater

Well someone forgot to tell my car you cant do it because I pulled my rear end out and swapped it with a 2007 ZO6 rear and it bolted up just fine. If you like I can post some pictures of it.