When I was a Ford zone rep in a rural Michigan agricultural region, t saw a bunch of those pickups, even nearly 20 years after the fact (the "unibody" design only lasted for the 1961 through 1963 model years). So I asked my dealers about it and the story I heard from several was that Farmers would buy the 1/2 ton F100, then overload load it with straw bales and other cargo as though it was a one-ton pickup...combine that with driving in their fields over plowed rows, and yes, there were some resulting body integrity issues. Of course, Ford had already made the F350 (1-ton) pickups in those years with the separate cab and bed...but apparently (my conclusion) the farmers did not want to pay the price of the truck properly equipped for their loads. Thus, in following years the return to separate cab and bed for all F-Series pickups starting in 1964, and also the engineering of 1/2, 3/4 ton, and 1- ton pickups to carry much more than their rated 1/2 ton, 3/4 ton, and 1 ton of payload! TB