rear end vibration

[stang_guy_95]

I have a pretty bad vibration coming from the back of the car. It gets a little worse with rpm's but it is mostly noticeable with the MPH. It starts to get really bad at around 90 MPH and gets continually worse. It almost feels like the exhaust is hitting the frame at first but the vibration gets pretty violent and it feels like it's coming more from the middle of the back end. I have a fairly new aluminum driveshaft only a few months old and the U-joints seem to be okay. I checked the exhaust and it is secure. The transmission and rear end fluid levels are good. I did notice some rear end fluid coming from the front of the rear end. I believe that the problem might be from the pinion bearing and/or seal. I have not gotten a chance to tear it apart yet tho, I will be doing that this weekend. Anyone have any other suggestions as to what might be wrong? Any help would be greatly appreciated. Thanks, Jason.