1999, F150. I have a new core support to put in but I don't want to weld it in like the originals were. I also don't want to use any of the new structural glues\adhesives. If I want or need to take it apart again I want to be able to do it without being destructive which welding and adhesives would require. My alternatives are rivits, machine screws with nuts and washers, small machine screw sized nuts and bolts or sheet metal screws. I'm leaning towards the sheet metal screws. Anyone have any thoughts or opinions to share on my choices?

 

All the older vehicles were bolted in place. I'd be drilling holes and using the shortest bolt with washers and a locking nut if I were doing it.