I have that exact Tamarack box on the rear rack of my 500. It fits perfect. I drilled holes in the bottom of the box and attached it with U-bolts to secure it. I haven't noticed any water getting into the box, however, I have not had it completely submerged. One of my hinges was a little loose, but a piece of electrical tape wrapped around the hook tightened it down nicely. Overall I am happy with it. There are pics in my gallery.