Truck is making a loud whirring noise at low speeds that seems to abate once accelerated. Is comming from front of vehicle/engine. Thought it was tranny but makes noise in park/neutral as well and reacts to pressing/releasing gas pedal...differential? HELP PLEASE

So is the noise speed dependant or RPM dependant? I think you're describing a bad driveshaft support/bearing.

Thanks...seems to be both; speed & rpm. Noise goes away at higher speed & rpm but at when in 1st/2nd gear, low speed it coincides with slight press & release of accelerator pedal