Dual Cab Racks rattling

Nat - I slipped thin, sheet-metal shims into the gap, cut to size to match the sides of the RHS and drilled to allow them to be held in position by the retaining pin.
You need to grease them, or they'll jam the RHS in the receiver with dirt and rust after a few months without removal of the hitch.

Cheers, Ron.

Drill a hole in the bottom of the receiver, weld a nut over the hole and put a bolt into it and when the tongue is in do the bolt up tight onto the tongue.

If you want to buy something look here Anti-rattle devices

I made my own version of the sleeve type.

Near the front of the receiver drill a 6.5mm hole and top it 8mm. The wall thickness is sufficient and then use a short 8mm bolt tightened to eliminate the movement causing the rattle.