Can't find a definite answer. Rear end code says my truck has a G80 limited slip 342 gear differential. But have read not to use fluid with LS additive, other places say yes use LS additive. Even read a notice from chevy saying not to but have heard that a new notice has been put out since then. It calls for synthetic 75w90 but since idk what the heck to put in it I opened her up sprayed her out with parts cleaner and refilled with 80w90 conventional valvoline. Two quarts without LS additive and almost a whole nother quart with LS additive. Since I cleaned it out I will just drain and refill if I have find out what in the world is supposed to be used in it. Anyone know for sure?