"The mounts need to be BOLTED to the frame and you need metal tie downs." Metal ties from an underframe belly bar to the eyebolts on a truck camper -- chain, hooks, eye bolts, turnbuckles, all can be found in hardware stores most anywhere in the USA.
http://www.etrailer.com/Accessories-and-Parts/Brophy/TDHP.htmlThis kind of hardware.--- Finding a belly bar if an old one fails or if you need to fasten a truck camper to a pickup bed ASAP, that is another matter. There was no easy or straight forward way I knew of at the time to fasten a wooden beam to the bottom frame members of a pickup truck bed. The metal belly bar I got came with specially fashioned strong brackets that worked very much like U-bolts to keep the belly bar in position.
--- After I tightened those turnbuckles between my camper and my wooden belly bar for the week that I used wood, I detected no evidence of movement or sliding. For the first 20 miles or so I stopped repeatedly & re-tightened the turnbuckles to take the slack that did develop, until there was no further slack. I grant I did not exceed 55 mph and only drove on smooth roads.