whats that noise?

[blumule]

ive been noticeing a low resonance type noise , kinda a like a moaning sound at highway speeds whenever i let off the throttle. doesnt do it at speed or accelerating , only when i let off gas. doesnt last long and disappears when i give it gas.Whats up? trans bearing? rear end? u joint? Can kinda feel it in my foot at pedal. Not sure though.

[basketcase0302]

Much easier, (and more dangerous) to diagnose noise like this on jackstands. I'd start with checking all the fluids, (tranny/rear axle) and check all your u-joints to make sure they have plenty of grease.