:help2: I have a 2002 2500HD LB7 D/A with 70,000 MI. I checked my differential fluid levels on my last oil change and they are a bit low. I have not added or changed the diffy fluid on either end since I purchased the truck 20,000 miles ago. I plan on draining both the front and rear and refilling with Amsoil. My question is first, how much should I anticipate buying in order to get both filled up. Second : According to their website the front would take either Severe Gear 75W-90 or 80W-90 and the rear takes Severe Gear 75W-90. With the limited slip rear, do I need to put in the slip lock additive with the Severe Gear 75W-90? :chevy:

6 Qts. 4 rear/2 front
Front diff came with 80w90 dino oil from factory. 75w90 synthetic is fine in the front. Rear is 75w90, some use 75w140 for towing heavy in hot weather. As for additive, the rear diff is a locker and no additive is necessary. Hope this helps.

That is everything I needed. Thanks for the info!!!

Mobil 1 syn 75w90 in the front and rear in mine.