So after some extensive researching and reading. I'm strongly leaning on getting the rear Diff from a 2005 STI with the 3.9 ratio. I've read that many people use this diff, and it has been but not behind an lsx motor. I'm planning on having a 5.3l with around 350hp, so it should hold up. But I was wondering if any other members could chime in who have this set up.