First off when i give it gas in park there is a vibration coming from the rear end, also there is a winding noise coming from the behind the instrument panel, and the speedo gauge bounces up and down after driving on the highway and then to slower speed roads, and last the a/c only blows hot are, i turned on the a/c and watched the compressor, nothing happened. Could this mean that there no freon, or is the compressor bad?? Thanks for the help..

rear end maybe bad u-joint,bad speedo cable, no freon in system maybe, or bad electric coil on comp.

the speedo cable making the noise i have that problem too although it only seems to happen when its really cold outside when i first get it running in the winter. after the truck warms up (including the air inside the cab) it usually seems to go away. on summer days it never happens at all.

btw the speedometer jumping is just the nature of the beast... they all do it its just the way they are...