I am a big Nissan fan. Been waiting for these guys to put out a "tweener" as they call it. I have owned/duramax, power stroke, gassers, ect. half and 3/4 jobs. don't matter who makes 'em, takes a version or 2 to get the kinks out. My new XD is a Pro-4X gas. Noticed a gap between the tailgate and bed "you could throw a dog through." Both sides. Ideas on dealing with this?