You will likely want to use Motul 300LS or something with an LSD additive for the rear differential. I use Motul 300V for my manual trans and Redline 75w90 LSD in the rear. 75w85 is also acceptable according to the UM but I can never find it on shelves. I forget exactly what the science is and where I've read it but I know that the additive packages for LSDs are different due to the mechanics, and it's important.
Also the stock fluids in the differential suck, and you'll want to replace them at least every 20-25k if you drive it hard, more often if tracked, although after 20k based purely on how it looked while draining last week alone. But the magnet was sludgy enough I'm glad I changed it just shy of 20k.
Also if you look up UAs on Royal Purple you may want to shorten your oil change interval. It shears faster than other synthetics. I'm running it myself right now because I got it dirt cheap and tax free but I change it at 5k-ish
Edit: for refrence, RE: Royal Purple:
http://forums.nasioc.com/forums/show....php?t=1302957
http://forums.nasioc.com/forums/show....php?t=1238027
http://forums.nasioc.com/forums/show...referrerid=767
http://www.bobistheoilguy.com/forums...&Number=894114
There are people who swear by it. I've used plenty of it myself without issue, not running OAs, though (though I plan on starting soon). However especially in forced induction applications and even without, there are an awful lot of OAs that indicate either that they aren't consistent or that at best, they aren't worth what they're charging.
If you can find it at a bargain and considering you're running an automatic, I wouldn't worry about it too much. But I would be wary, especially in a dusty hot climate and for performance driving applications.