If "diff oil" means the oil to put in your differentials, one of the most important things to be sure of is that it is GL-5 (and not GL-4, which would more commonly be used in a manual transmission).
Careful inspection of the oil you drain out may be helpful.
Changing the front differential oil will probably require removing the stiffening plate, along with the famous (or infamous) bolts. Set aside some time before delving into that topic.
