Vibration/grinding sound while accelerating

[jsred]

I have a 2004 LS that is giving me fits because of an odd noise that occurs while accelerating.. Not service affecting, just annoying.

It started out accelerating after 35 MPH, but now can happen during various speeds while driving (not in reverse). It sounds like it is in the front of the car.

At first it was a grinding sound, the dealer replaced some parts in the exhaust (my guess would be where it bolts to the front).. The noise kind of went away.

Went back to them and they replaced parts in the rear differential.

It is faint but still noticeable. It sounds like a vibration or a grinding sound..

Does anyone have any ideas? The dealer is going back to Ford to see if they have any ideas.

Thanks in advance.