...not sure what is going on ...04 2wd with a ton of miles (180k)...relatively no problems since the day we drove it off the lot.

Noticed that when we are backing up AND turning to the right, it will sound like you are driving on gravel. Turning to the left and backing up straight it won't do it. The other thing that is more noticeable is that is seems like the rear tires are spinning more often when you take off. We put some new Cooper H//T on it about 20k miles ago so I wouldn't think that is the problem.

Any ideas?