My pin box is 32" from center of pin to the end. My truck bed is 58" wide. So I have a 3" deficit. Or 1.5" per side. FWIW I have a 1716 style long pin box. I also have 6" of clearance between the 5er and bed rail. In 3 seasons and close to 10,000 miles I've never had an issue. The rear of the pin box is cut on a 45* angle and that gives me some extra clearance. The cut angle helps allows some of that 1.5" deficit to be useable. I make certain to watch when turning sharp. JMO but you need to look for a shorter pin box than the Lippert style 1716 if you want to be certain that the end of the pin box won't come in contact with the bed rails.
