diff/trans lube

What transfer case? Do you tow? What does your owner's manual say?

If you have the option of dino or synthetic choose synthetic.

SelecTrac transfer cases use ATF+4 (ONLY), for towing you should be using Synthetic 75w-140 gear lube. Add friction modifier if you have limited slips and your synthetic does not already include it.

FWIW AutoZone carries Valvoline brand ATF+4 for $3.69/qt.