thanks bud, been reading all night and i think you hit BINGO! thx again.

 

Please update when you find out definitely. It sounds similar but I dont work for Aamco so i might have translated your grinding wrong.

EGH - PTB

 

I have the same exhaust and was having a rattle noise also. Mine (08 unlimited 6 speed) ended up being the exhaust pipe itself. The hanger was to long and the pipe was resting on the metal cross member under the drivers door. Was barely touching but under certain situations it vibrated just enough to annoy the shit out of me. I ended up bending up the factory hanger slightly and putting on a smaller rubber hanger. Sounded exactly like a heat shield too. Didn't look to be touching but when under I had someone feather the pedal and narrowed it down.

 

I had what sounds like the exact same issue. Start accelerating, it would start rattling around 2k rpm. If I accelerated hard it would go away. Made the sound both in gear and in neutral. I just went with the metal hose clamp fix, figured it only cost $9 so I might as well. Took 5 min to put them on and the rattle is gone. Whole new jeep.....