There does seem to be a vibration associated with the sound but it is very subtle. I can feel it in the arm rest. The tranny fluid level seems good although it find it hard to get a consistent reading (I drive a bit and then check it at idle). I do want to change out the rear diff fluid. I have never checked it. There don't appear to any leaks..unless its been dry since she got it. The noise is relatively new.

I just rotated the tires. I took a short ride and got some noise at 70mph but it didn't seem to vary like I described before. I may not have driven it long enough though. My girl will be taking an hour drive today, so I will get a report from her. A wheel bearing noise would change with turning? And be noticable at lower speeds? Thanks for the input.