1998 GMC Jimmy SLS
Unfortunately it's not the good type of grinding.

Everytime I go over a decent size bump I get this awful grinding noise. It's starting to get worse. But this grinding noise only occurs when I'm going 15 to 35 mph and hit a bump on the passenger side. It stops after the car hits it and it last for about 1 to 10 seconds. Its definitely coming from the mid to rear end of the car. I dont see anything lose underneath it. The car seems to sway when making a a right hand turn. Could it be a bad brake pad? Is a shock or axle shot or going bad? Is my transmission gonna explode while I'm driving? Please any help would be appreciated
Thank you again

 

Axle bearing, maybe? Try jacking the truck up, and spinning each back wheel, see if it feels rough or you hear the noise. Also, does the grinding get louder in a corner?

If that's it, pretty easy fix. You have to open the diff up, though, to get the c clip out.
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Does the grinding noise continue with a frequency that seems synchronized to the speed of the vehicle or is a grinding as the suspension goes up and down?

Extra swaying could indicate a bad shock along, especially if the grinding is associated with the suspension going up and down.

 

Hey dunno if you figured it out but I had the same problem and I pulled the wheel, caliper, and finally rotor off and all it needed was the parking brake replaced. It was so worn out that it would catch at random points inside the rotor. I replaced it 3000 miles ago and haven't heard anything since. 35 bucks at Napa and it's great now. Hope this helps!

 

He was last on in Dec of 2019... hope he's got it, but thanks for putting up and option for others to look at!