Just did a differential upgrade to my '05 as well. Stated oil capacity is 1.3 liters. Use 41 ounces of synthetic GL-5 gear lube (I used 75W-140, but Unitrax said some brands of 75w-90
are also fine), first adding 4 ounces of Mopar friction modifier (P/N 4318060AB) for a total of 45 ounces. If the diff is sitting level, you can't overfill since the plug is on the side and will
start leaking back out as you fill it, which is always fun. Pour in the friction modifier early so it's not what is leaking back out! This is all easier to do before bolting the differential
into the car, otherwise a fluid pump is useful. Torque on both the drain and fill plugs is 15 ft-lb.
I refuse to start a "Best" brand of oil discussion, but I would not skimp here.
