Robert.
Short hex head lag bolts are used to anchor all the roof safety rails and brush guards. Can either be flanged, or plain, used with a flat washer. They will need good, solid 1/4-inch plywood directly underneath the outer aluminum sheet metal roof skin to work at all. Once water gets into that upper layer of roof plywood and the rot process starts, nothing you bolt or screw down up there will stay in place very long. The box simply flexes too much when the vehicle is on the road.
If you cannot get any hardware to grab when trying to mount those fittings, you have a problem.
David
|