Like I said above. I'd go for 4.9. 4.6 won't make that much difference.But if you have the parts <img src="/forums/images/graemlins/scared.gif" alt="" /> You can find 4.9 fairly cheap. Like $150-200 per axle. The fron prob be direct swap. No need to set up gears. As to rear one. If you get 3rd member out of sport I beleive it would be direct swap as well. Added bonus would be a Hybrid LSD all 3.5l MSport Limited came with, or you might get lucky and get rear locker. $150 is cheap for labor though. I assume this is only for setting up gears you'd have to disassemble yourself.