Truck box knob spacer

thingiverse

I use this PETG printed spacer along with a 5/16-inch threaded knob to lock my truck box down to my truck bed rails. (You may need to drill through your plastic rail covers, but my metal rail already had the threaded hole beneath the plastic covers.) It forces the box to a centered position and keeps everything held down very tightly, especially if you add a nylon wingnut or print your own PETG threaded block (not included in this design).