Rear differential

1997, z71, 5.7l, Im changing both front and back diff.On the rear i Do NOT have locking diff.Do i put any additives in with the 80w90 gear oil. And the front will just take 80w90 correct!! thx jeff

You do not need any additives (front or rear). Check the owner's manual. The rear may require 75w-90. 80w-90 sounds right from the front.

//2000CAYukon