When I purchased my truck, before 5th wheel or hitch, I installed "industry standard bed rails. They had detailed instructions for installation, which involved measurements on the frame and installation of brackets to the frame. The last thing was to bolt down the bed rails to the frame brackets thru the bed. The instructions never mentioned the axel, but after installing my Super Glide hitch, the pin ends up about an inch or so in front of the axel center line. The multi page instruction manuel had specific instructions for Ford, GM, or Dodge short or long bed. I assumed industry standard was just that ans if you followed instructions it would place your hitch where it was supposed to go.