I have had a mount off of the side of the box on my pick-up since new. About 3 weeks ago someone attempted to remove it without luck. But there was damage done to the box side and the mount was deformed and pushed up into the edge of my cap. So I had a shop construct me a new one made from 1/8 stainless 6" wide with the required bend so it won't rub against the cap of the cap. The new style of caps have a fiberglass "flange" type of thing around the edge to the mount had to be bent down some. It was pricey but I contribute that to me being in the oil Province where anything involving steel is expensive. With the new MFJ ball mount it worked out to about $130 + or -. It is solid with 6 #10 stainless bolts holding it into place.