So I get this whine when accelerating and it sounds like it comes from the rear end... so I talked to this guy and he recommended putting some gear grease in the rear differential, so that's what I did. It helped a bit but the whining is still there (significantly). Is there anything else I can do? He said It was probably just gone beyond repair and in a little while (5 or 6 months) it would just stop working. Any thoughts? Thanks

Let me get this straight, you put in paste-like wheel grease where you would put in your rear end oil?

Check your wheel bearings noises tend to travel along metal parts and make it seem they are coming from a place they aren't.

it was the right stuff I put in... you get a pump and it's thick and smells bad... how do you check the wheel bearings, do you need to take the wheels off? and where are they? Pictures, anyone?

Sorry, mispoke, axle bearings. They are the bearings between the axle and housing, at the end of each axle tube. I'm not sure what the offical check is to make sure they are ok, but I'd start by lifting the car in the middle of the rear axle (make sure you put stops behind/infront of the front tires!) put the car in gear then have someone sit inside and rev it while your in the back listening for the noise.

Also, while the car is in the air, grasp each wheel and move it back and forth to check for excessive endplay.

Had exact same noise, in my case it was a trashed pinion bearing. I purchased my kit from Randys Ring and Pinion. But for my second rebuild will be going with Reider Racing due to their available options.....Dave

How low on oil did the unit get? How much new oil did it take?
Worse case, if the unit gets real low on oil, the gear teeth and bearings over heat and score, that throws the gear mesh off and the gears start making a whine.

I have seen this happen before and had those noisy rears last many more year as long as oil was kept in them. Most of the time I swapped them out after awhile because I could not stand the noise.

You would have to pull the rear cover off the unit and inspect the gear teeth to see if this is what has happened.
DD