Chevrolet Silverado Custom 1500

[AMM21]

Brand New Silverado. Drove it home and then back to dealership. Had 4 miles on it. Was making a grinding sound in rear of truck when hitting speed bumps and when reversing. I dropped it at the dealership at noon yesterday and they still have it there. Is this normal?

[Sjordan]

I would definitely not consider a grinding noise on a brand new truck normal.  

[AMM21]

They say there is nothing wrong with it. Seems to be normal when hitting a bump or reversing down a slight hill. Feels like a grinding sound or maybe something is loose but they say otherwise

[Sjordan]

I am at about 9k on a custom trail boss and have no such noises.