Mini-project - plastic utility box in bed

I've been trying to work out whether I want a shell for a while, then I thought I wanted a retractable tonneau only to discover it's about the same price as a shell (around $1,500). I'm not ready to splash that sort of cash on a truck that I may trade at some point (and not sure if it would suit my needs anyway).

So I went to Wal Mart yesterday and bought a big plastic box which I can store stuff in to keep it dry on our Christmas roadtrip to CO. It's pretty sturdy, has an eye for a padlock (not overly secure but a deterrant) and at $45 was a whole load cheaper than a proper X-plate box.



I want to fix it down with thumbscrews to the bed, so I can remove the box easily if need be (and I don't have to get under the truck to put nuts on the bolts). I bought some jack nuts to mount into the bed that will give me a female thread to screw into. However the jack nuts aren't really man enough, I stripped one of the threads mounting it. I don't want anything sticking up too high from the bed - maybe a half nut but that's all. I will drill the holes in the bed in the trough part of the ribbing so I can slide equipment/pallets etc on the bed when the box isn't there.

Any suggestions? I tried looking for some threaded pipe with both a female thread on the inside and a male on the outside but it doesn't exist. This would have worked well with 2 half nuts sandwiching the bed. I'm also considering the idea of welding a nut to a plate then glueing the plate to the underside of the bed; this will hold the nut in place permanantly.

And suggestions?

 

Self tapping screws

 

Thanks for the suggestions - I ended up buying some car air filter nuts and gluing them to the underside of the bed.

On a side note - I didn't know that the beds were all plastic. Does any other mfr do this?

 

nutcert...basically a cylindrical(sp?)nut. drill a hole, use insert tool(similar to a rivet gun). The shell of the nutcert expands holding it in place. It ends up being a flush mount threaded hole to bolt to. We use them on our fire engines all the time to mount tools. I'd show a picture but I'm at work right now. You will probably have to find something under the bed that is more secure to drill into other than the coposite bed. Just an idea...you might be able to rent the tool from somewhere like autozone.