While I wont disagree that the beds are a different widths, My biggest problem with the cover is the length front to rear. I have to shift mine as far back as possible, while not comprising the seal at the front, to get it to contact the tailgate. The inner rubber seal running side to side just barely touches the inside of the tail gate. The open area at each outer edge leaves in a lot of water in too. This is a really disappointing level of waterproofing.
I usually run an ARE over the rail hard cover and knew I wouldn't be getting the same level of waterproofing but the fact that it doesn't fit well really aggravates the situation.