75w90 synthetic and call it a day. I run ST Synthetic 75w90 in the front and rear on my older 2nd gen Taco, but they're still very similar to your setup. Mobil 1 75w90 is also popular. AFAIK you do not need a limited slip additive as they use the ABS system for mimicking LSD. Most syns have the additive already in there, but there's no harm. You could use the Amsoil if you expect to be running the snot out of it, but just for daily driving and snow, IMO there's no need to spend that much...
The transfer case does require a different fluid compared to the older years, but there's a recent thread with good information.