Differential cover

[fisherman]

I just bought a differential Black Powder Coated cover with added oil capacity for the rear differential. Of course I opened the owners manual and found the specs, GM # 12378261 SAE 75W-90, synthetic. That's okay. Went to Capacity...not listed. Called Hummer "hotline" and they did not know. Called my Hummer Dealer and he said "three quarts". They have the gasket (GM # 12479143) for $29.95 and the oil is $29.25 per quart. After e-mailng the manufacture of the cover, the new capacity is approximately 3.5 to 4 quarts which should allow for a cooler temperature and stronger construction. They said the gasket is reusable. Has anyone heard of the gasket not being replaced? That really sounds dangers to me, if not stupid. Educate me. Oh, Auto Zone carries the oil for $8.50 per quart.
The "fisherman"