Depends on which part of the truck the noise is coming from. Could be an u-joint, a wheel bearing, a failed transfer case......
Bad shocks
check shocks
Causes include a weak battery, loose cables, failed starter.
Brakes
Most likely your upper shock mounts. Get them checked over.
Check to see if your trunk is open or if the clasp that holds it closed is loose.
It may me that your brake is on.
grinding #
it is the creation of new landforms
If your truck is 2wd than check the bearing, hub assembly. This is considering that you have the balance and alignment checked at a shop already
Depends. Do you always hear it or only when speeding up and slowing down. I have the same thing on mine but nothing is wrong with it. It's the transmission that's making the sound. Nothing to worry about unless you start to get a clunking or grinding sound, then you have problems...
check rack and pinion. sounds like it needs to be replaced.