Bed replacement fit issue

[QuakerState]

I am in the process of assembling my 1972 Jimmy replacement bed sides and bed floor. After placing the floor I am noticing the body mount located in front of the gas tank has a gap of 1/4" on each side. I have not tightened up the floor mounts so the gap may improve with tightening. I measured the frame and the frame is straight, I am going to measure the individual mounts tonight. I am going to permanently mount the bedside so I thought I would ask the group if I should consider anything else to correct for the gap in the mount?