Now it is time to cut the floor to fit. Ford was using the exact same stamped floor for the long bed and short bed. Only the carriage bolt holes are different. There is a set of stampings for the short bed in every long bed floor. Weld up the old holes like I said earlier, and 2 inches aft is the new bolt forms. Weld the underside box mounts with the measurements from the short box. Cut the bed floor from the front side only. The wheel houses from the long bed must be removed from the floor and moved aft to fit the short bed.
Slide in the floor and then check measurements you made while drinking beers. This will add to the merriment of your girlfriend when the tape measure sails over the neighbors house. Personally, I lucked out.
However, the bed floor warped after the massive beating into shape and reweld of box mounts. You have to ensure alignment before you start welding this puzzle back together. If not, then when you bolt it to the frame it will be under tension, prone to cracking, and will cause oil canning. I just used 4x4 posts and straps at the mount stiffeners.
Clean up the wheel houses, bang out the dents and prepare to weld in countless spotwelds. I use zinc weld through primer between panels. Clamp in the wheel houses. Do not tack in one single thing until you are positive of position. Then drink some beers.
