I have this cluncking, crunching kinda hollowish sound pulling away or stopping at a traffic light. It also happens pulling in my driveway which is again slow speed. I thought maybe it was my U joint since I replace one of the two last year. But I pulled my driveshaft off and and spun the u joints around to see if it made any sounds and they sounded ok with no noise or resistance. I also noticed my Transmission fluid was down 1/3 of a liter so i'm hoping it's nothing to do with that but i'm thinking not. I also spun my rear wheels and the rear end sounds fine so this all leaves me kind of stumped. Cars a 87 Iroc with around 450-500 hp and transmission was built to handle 500hp by my transmission guy.

 

Look at the front suspension first; it's likely there's something worn/loose. While you're under there, check your brake pads and caliper mounting hardware.

Regarding that u-joint, if you're going to replace one of them, IMO it makes sense to just replace both while you have the driveshaft out.

 

Second that. I'd start with a good look at the wheel bearings and brakes. Also, make sure your K-member bolts are tight. When I got my car, two were backing out.

 

I had the same issue with my 87. I replaced the rear axle bearings and it stopped.

 

Im going to replace the u joint that wasn't replaced then both will be done. There's probably only 500 to 1000 miles on the replaced one. Im lazy these days and had them both sitting there at the time. And I agree that both should have been changed. Things changed in my life a few years ago that turned me into a lazy individual...lol. I'm going to run the car and see if the noise goes away and if it don't pay closes attention to some of the items mentioned.