If you have enough heavy stuff in your box it won't slide. I had mine drilled to the rails on my F150 then had to remove it for some large cargo. Put it back on intending to screw it down the next day and never got arounmd to it. Transfereed to box to my new SD and never bother to screw it down and it's not moving around!

Frank (Old Dog)
'02 F250 Lariat4x4 Crew V10-Auto Long Bed
'95 F150 XLT

 

Weathergaurd makes the best boxes out there. They are solid, built with heavier gauge aluminum diamond plate than the others, and have dependable lock systems. They also have a hell of a selection. I believe someone has already posted thier web site above.

 

Big Green 99 f-250 4x4

I have a DeeZee gull wing and love it. Aluminum color. If you want to mount to the bed rails without drilling into them, Get 2 -3 1/2 in long 3/8 in lag bolts. Stick the head in a vice and bend it making a hook. Drill a hole in the box on the inside just to the inside of the bed rail. Slip the bolt thru the hole from the bottom of the box letting the hook grab the lip of the rail. Then get a washer and nut and bolt it down. Hope this helps install woes.

Tuna

 

go with a single lid, that sits in the box. they are way less prone to leaks as the lid doesn't sit up in the air stream atop the bed rails.

also, if in the future you decide to get a nice top for the bed you won't have to dicard your box