my bed has been trying to come loose ever since a little load shift incident a couple years ago. I finally got a torx bit and attempted to slide it back to normal and bolt it in. I had no luck getting some of the bolts loose so I decided I would just tighten the two loose ones and pick up an impact wrench later.
Well low and behold, the passenger side rear bolt broke loose from its rusty bind and came right out even though I was TIGHTENING it. Whatever it threads to in there is gone or very displaced. I couldn't tell much with a flashlight and didn't see any access to it from the bottom.