So in my 98 Yukon with G80 code, I have a rear axel seal leaking and am going to service rear end. Bearings, seals, fluid, gasket. From the AMSOil site, I have two quarts 75w-90 (ACD 10-4016) in my cart (ACDelco fluid, just using AMS site for amounts) but am conflicted if I need to order and...