Pull your center console and remove the plate that holds the shifters in place. Drive around and see if you can determine where the sound is coming from. It will be very pronounced if it is from the driveline.

 

exhaust in good good condition? especially around cats and heat sheilds?
did you do the playing card in the spokes mod?
also, have you recently run over this guy? if so....remove him.

 

"Name this sound! AUDIO INSIDE!"
_________________
Something from the Village People?

 

I would so love to find a 200 year old wookiee under my rover, just hanging on for dear life. Seriously though, exhaust is in good shape, yes I did do the playing card in the spokes mod but this noise just drowns out the wicked note from that. I just cant understand why it goes away when on the gas or brake and only starts on deceleration. Thinking I may do a diff/tc drain and fill to see if that helps, any thoughts on if that is the cheapest place to start? or most logical?

 

well, you could change fluids cheap and see if any teeth fall out, but more likely a bearing sound . you could see if you get any up down side to side movement at either end of the shaft/ output flange, but no vibration....

 

did you do the playing card in the spokes mod? you get point for that one.

I would look at the heat shield, it a fiberglass shield with tin foil on it. could explain the strange sound, i ripped mine off

 

Yes it sounds like a bearing. Something that's only loaded on overrun. (well... duh!)

PS, I listened to the noise, doesn't sound like the SAI pump.

Have a good look around, including the engine bay, you might be able to see the point of contact (metal shavings? plastic?). I did have a car make that noise once, the engine mounts were shot and the crankshaft pulley was rubbing on the body! On overrun the drivetrain will shift slightly and something could make contact that is not doing so otherwise.