I'm a bit confused, are we talking the seal between the tailgate and the rear face of the box?
I bought and installed an American tonneau fabric cover for my Bighorn and it came with an adhesive tailgate dust seal.
I noticed right away that when installing the seal as per a Youtube video, the seal did make contact with the tailgate.
My solution was to install the seal, by sitting in the box, with the tailgate closed, making sure the seal touched the tailgate.
It worked perfectly.
Note however-there will always be a leak sometime, someplace.
I bought and installed an American tonneau fabric cover for my Bighorn and it came with an adhesive tailgate dust seal.
I noticed right away that when installing the seal as per a Youtube video, the seal did make contact with the tailgate.
My solution was to install the seal, by sitting in the box, with the tailgate closed, making sure the seal touched the tailgate.
It worked perfectly.
Note however-there will always be a leak sometime, someplace.