My wife has a 2013 Xterra Pro-4x with automatic transmission. Last weekend at a tad over 40k miles, I finally was able to change out the driveline fluids:
Front diff - Mobil 1 75w90
Rear diff - Mobil 1 75w140
Transfer case - Valvoline MaxLife ATF
Transmission - Valvoline MaxLife ATF (simple drain and fill)
Engine - Mobil 1 0w40 and M1-110 filter
The fluids in front and rear diffs didn't look terrible, but the magnets did have quite a bit of debris. The transfer case and transmission also didn't look bad, but the fluid did look used up. I may do another drain and fill on the transmission at the next OCI for good measure. I have always changed the oil every 5k miles on this vehicle and see no reason to change that, but I may continue to change the other fluids at either 30k or 40k miles.