Rear Problem?

[concretebeatz]

2003 GT 5-Speed
My Mustang has 44,000 miles on it. I am having a problem somewhere in rear of my car. The car started making a grinding sound when I took my foot off the gas pedal to coast in gear,sound like it was toward the right rear area. The noise would stop when I pressed down the gas pedal or push the clutch in. The sound got louder so I had a mechanic
install the 4.10`s I always wanted thinking this was the cure. He inspected and re-used the original bearings. After the install the noise was still there, no change in the sound, Any ideas where this noise is coming from?

Thanks

 

[sgarlic]

Is it the driveshaft rubbing on some part of the exhaust?

 

[concretebeatz]

No, I jacked the car up and checked for any thing rubbing or loose before the install. Thanks..