Ok, that sound has been occurring consistently (and louder still) in the last two days as soon as I hit 60 MPH. Now I have a different problem. I hear a hollow metallic banging noise from the undercarriage whenever I go over even the smallest bumps. I wonder if the new exhaust piping I had welded on by Midas a couple of years ago is "coming off". Also when I accelerated in a tight left turn this morning into my office parking lot, I heard a metallic noise and it felt like something was keeping my right rear wheel from turning. I actually felt the car settle and then being pulled in that direction. I tried another left turn and same problem. However, when I turned without applying gas, the problem did not happen. I haven't had a chance to make a right turn to see if this happens to the left rear wheel as well (had to get into the office). Anyone have any ideas?