hmm vibration + noise could mean a u-joint. you can also check and make sure your leaf springs arent cracked/broken. there are plastic spacers that go between the leafs to keep em from squeaking, might check those. check the u-bolts that hold the leafs to the rear end. make sure the leafs are tight to the rear end. check your shocks. if its not any of those check your bearings/brakes. uh.. spare tire too, could be loose wouldnt be the first time someone had a weird problem that was a loose spare
. i think thats about it.