Vibration

[SIDE_SHOW]

The wheel bearings out of spec will cause the tire wear as will shocks...

Is the ride height correct? this will also cause a vibration although usually accompanied with a growl...

Is the driveline in phase/ time ? This will cause a vibration...

If you have eaton rear ends the yokes are bad about loosening up at least they used to be I don't know if they have fixed that on the newer models or not....



I would re torque wheel bearings they probably need to be done anyways

Same with shocks replace if you can

Make sure the driveline is in time/phase... I'm not very good at explaining this but all the yokes need to line up maybe one of the other members can explain it a little better

Check the ride height
I'm not sure what the spec is on a prostar but I know Mr rawze does

Chock wheels and release brakes crawl under the truck and move up and down on the rear end yokes if the yoke moves on the pinion shaft it's loose best way to tell is to look at the nut while you are moving it up and down....

Also the crush washer as Waterloo said I have seen this give fits as well.

Thats where I would start... But I'm no expert just what I've had to deal with

As Waterloo said you may just have a u joint that is bad but you can't tell that it's bad until high speed... .