Do I need any fasteners or hardware to install this?

The step bar is designed to slide into your 2" hitch receiver tube. You'll want a pin or bolt to lock it in place — check what your hitch setup already has. Most trucks use a standard lynch pin or receiver pin.

Will this step bar rattle or move once installed?

A snug fit in the hitch tube keeps it stable, but securing it with a pin prevents any side-to-side movement or noise. Tighten whatever fastening method you use before loading weight on it.

Can I use this step bar on a trailer hitch or just a truck?

Works on any vehicle with a 2" hitch receiver — truck, SUV, or trailer. As long as your receiver tube is 2", this step bar will fit.