The 42-47 half ton pickup frame and wheelbase are different from earlier; howevwer, the pickup bed sides are the same, but the fenders for the later trucks are located further rearward to accomodate the longer wheelbase. Why not go down the road and measure the length of the panel from cowl to the rear, so it can be compared to someone on Forbarn that has a 40-41 panel? I don't think Ford would have gone to the expense of strecthing the panel body when it would have been cheaper to source a shorter frame, just my two cents! In any case, good luck!