I was just driving this morning and started hearing a clunking somewhere under my truck? i cant pinpoint where it is but all i know is it doesnt make the noise when i give it gas, but as soon as my foot comes off the pedal the vibrating/clunking starts again, then i just touch the pedal and it stops? doeas anyone have an idea what it could be? thanks.

 

sounds like your u-joints

 

U-joints ore the rearend is coming apart would be my guess without actually hearing it.