If you want to do the swap as demon said then the way to go is a 09 Challenger diff, you will also need axles, hubs and a rear drive shaft section. The swap is fairly straight forward and does wake up the car... now the difference in drive between the two is not enough to pin you in your seat, but combined with a high stall converter and some decent motor mods it works quite well. I personally didn't want to sacrifice too much top end or cruising economy with my setup... I went with the SRT drive line and haven't looked back... and yes it is quicker... next trip to the track I'm sure will reflect it as well... where I struggled with my friends vette in past days and matched it at best, now I can get the hop and seem to retain the lead till 100ish (haven't pulled past that as of yet)... now obviously my converter did wonders for my launch but the rolling pulls I put down to the gears... I'm happy. FWIW... :-)
Johan Tune, FRI'd (Sidewinder & Street/Strip Heads), Ported SRT Headers & Gutted Mid's, EGR, MDS & rear 02 Delete, Custom Catback with Blastin Bobs SRT Pipes 4" tips, 170 Tstat, Ducted AH CAI, Big Bully Catchcan, 3.06 diff w/upgraded axles, 2800 stall 'verter, MTCM, Tranzformer, Brembo GT w/D&S & Hawk pads, 5/15% Tint, SRT 20's, SRT Spoiler & Bumpers, Custom Stainless Grill, 6k Fogs, Eibach drop..what's next?
0-60 - 10.8 secs with 650' of rubber!