Ok, I'm 95% sure what you have is a material (bolt) fatigue problem due to vibration. This event will fail just about anything that is trying to hold it....unless its rubber. This is why vibration control in equipment is its own special field of expertise.
So you need to make sure all the brackets the guys already mentioned are in place....or a sturdy equivalent. Then you have to check and make sure the power steering pulley is not wildly out of flatness as it runs.
Then, if you have a buddy who has an equivalent truck or set up, check to see how theirs runs and vibrates...watch carefully. Then use that as the datum point for determining if your own is now operating within normal parameters.
Good luck and keep us posted.
Coley
