The rear end noise you hear is not normal. It is an issue DC knows about. The fix is to remove and replace the complete rear end. Mine was replaced after one test drive to confirm I actually had the problem. The new rear end took about 10 days to be delivered to the dealer. The car was in the shop one day and everything has been okay since.

There is an old thread from about two years ago on the same topic. Here is the first and last post:

- With the windows up, stereo off, cruise control on... does anyone ever hear a steady noise at speeds of 60 mph and higher??? The noise I hear sounds like a low pitched humming sound that goes away if you change throttle position. Noisy fuel pump maybe??? Anything that can be done about it??? Thanks for any inputs.

- Update... The noise is coming from the rear differential and will only get worse as the car gets more miles on it. Took mine to the dealer yesterday. They pulled off the diff cover... way to much metal shavings etc in there. Corrective action: R&R the rear end. Parts should be here in a few days. Chrysler is well aware of this issue so anyone hearing the same noise, get it checked out.