5th wheel mounting holes in bed

Thank you for your responses. The previous owner took the mounts as well as the hitch coupler. The 42" side to side does put the holes outside the frame rails.

Unless the frame brackets are still there under the bed, I think it would be best to abandon the existing holes, and then choose the hitch and mount of your choice. A body shop can fill those existing holes for very little cost. And if you're interested in a spray-in bed liner, now would be the time to get that done too.

SPECULATION HERE. It may be that someone did a shoddy installation of standard 5th wheel rails. The dimensions are somewhat close to outboard hole spacing but not not exact. I can't justify the 24" front to rear though. Bed rails do not mount to the bed but rather through the bed and on to brackets that are mounted directly to the frame.

I installed brackets and rails on 2004 Ram with 8 ft. bed. To position the rails correctly over the axle two of the mounting bolts go through an inverted hat section bed brace. To keep the brace from collapsing shims need to be mounted inside the hat section which at first looks impossible. It took me over half an hour to develop a procedure for installing the shims. All the mounting bolts use 9/16" holes. Could be the installer enlarged the holes and dropped the shims in from the top. Just 4 bolts are insufficient to secure the rails. Curt, my bracket supplier, offered no guidance as how to install the shims in the instructions.

I would take it in and have new rails installed properly then you have your choice of hitches. It is important that this is done right that is why I did it myself. In hindsight, it took me six hours to install. I could have completed it faster if I had a lift and a helper. If needing it again I would pay to have it done.

Pullrite, per their website, has the super rail system with brackets available for new Rams (2011 I believe). The dimensions are different though: 1 5/8" holes, 36 1/2" side to side and 22" front to rear. Are there frame mounted brackets underneath and directly under the holes?