I have a 1997 camaro rs and there is a grinding noise in the back it is not the breaks and there is gear oil in the diff. What else could it be and I really dont think it is the wheel bearings either.

The brakes and wheel bearings are the first things I'd pull apart and inspect anyway..

I agree with Geezer. You very well could have some major problems taking place inside the differential. The sooner it is taken care of the better off you will be. Hopefully the noise is just a bad bearing. The longer you drive it the more damage will increase. I doubt you would want an axle to depart company while cruising.

it sounds like it is coming from the driveshaft I put it up on jackstands and let it idle and crawled underneath. It is a constant grind/rub

You might drop the driveline and check out the pinion bearing area. Do you have a stethoscope? If not, a short piece of rubber hose will work. You might also try to syphon off a bit of rearend lube and see if you have any metal filings in there.