[finall]

Thanks for the advice. Yes, the UCP (Skid plate) was originally mashed against the exhaust, but the dealer fixed that. So there is now more than 1/2" space between the two, with no chance of contact.

But after repairs, the UCP still makes a vibration somehow. Much less than before, but still noticeable.

Something else is wrong. I wonder if body or frame flex could be torquing the UCP and creating the vibration. The UCP bolts are tight. I have no idea how it could be causing a vibration in its current state