Again, mine (GM diff gasket) was already torn and pretty badly stuck on the mating surface of the diff and cover when I took out the cover. It looked like a coated paper material. Of course, new gasket seemed same. When I changed the transmission fluid, the gasket was like a thick plastic/rubber. The gasket of AAM rear diff looks similar to the transmission gasket. Highly doubt GM one is reusable… Anyone who has SU8 plans rear diff fluid change, get a new gasket before taking off the cover!!!