My father had a Ford F100 that I think was a '64 model. Other than putting heavier ply tires on it, it was bone stock. I remember when I was about 17 dad sent me to the feed store approx 30 miles away to pick up his order. When I arrived they brought out 3,000 pounds of cattle feed in 100 pound bags. I was able to stack them in the bed hanging over the sides a bit so I could keep as much forward as possible. I ended up with the load being a couple of feet higher than the top of the cab. When I was about to leave they said "don't forget the salt". It seems dad also ordered 500 pounds of salt also in 100 pound bags. No way was this weight going on the back of the truck, so I put the sale in cab floor and right hand seat.
Did it drive a bit light in the front? You bet, but it handled the load fine. Would I try that with a half ton model today? No Way!