I hope you folks will be kind enough to help me out with this question. I need to know the distance between the bed rails at the top of the bed near the cab for Chevrolet, Ford and Dodge. This dimension seems to be missing from all the drawings I can find. Unfortunately I'm in the UK and can't just go out in the parking lot and measure them since are very few over here. Thanks to anyone that could take the time to measure this for me.