Squeak in the front end

[andrewpclayton]

There is a squeak that is like a fluttering chirp in my front end somewhere. It happens only when the compression of the engine is slowing the truck down, and my foot is off the gas. If i give any gas at all, it stops, and if I put it in neutral it also stops.

From what i can tell, its not in the dash.. not anything i can reach and hold secure.
I cant reproduce the sound in any way other than driving.
I did try to clean underneath the truck with degreaser.. around the trans and brake area

Does this sound familiar to anyone?