I just found out, doing an all-fluids change myself, that the rear
differential on my '04 Z71 Avalanche (4.10 locker) has been 2 quarts low
since I've had it....which is 26 months now. No leaks or seeps anywhere on
the diff. Lest I be accused of lack of due diligence, I took it to the GM
dealer a month after getting it an had all the fluids "serviced"...including
the front and rear diffs and the transfer case. After spending a day under
there I can tell with 100% certainty that none of the drain plugs on the t/c
or front diff have ever been off. They are as pristine as they were when
they left GM's Mexico plant. Ditto for the rear diff plate and fill plug.
All along I though a certain amount of diff howl was normal with the 4.10's.
Now I wonder if it was low fluid all along. Question: One What's the
capacity of this differential....how much fluid has been in there with 2
quarts missing? Question Two: What's the likelihood of permament damage to
the rear end? I wiggled the rear wheels while off the ground and the wheel
bearings seem tight. No real noise or play apparent.What are the odds this
has damaged the diff?