i just installed the manual retrax for my truck. wasnt too hard to do. looks great. u cant lock it in any position as the website states with the rambox. u would have to drill holes in the rambox guide rail. definitely not water tight. no huge puddles in bed, but it does get wet. i would suggest ordering their tailgate weather strip and use it along the top of the tailgate. u will not be able to remove it if u need additional bed space without unbolting everything. works fine with line-x and rambox cargo divider. bought it for security so i am happy with the product.

paid $849 for cover, $70 to ship, $23 for tailgate gasket

 

Second time owner of the Retrax. My old one was on a Titan and I also got a little water in through the tailgate. I haven't had the Ram in the rain much, but this version seems to be a little more water tight than the last one (five years ago). I wouldn't have bought a second one if I didn't like it.