the date code would not been a normal production line item at least painted like that, i would bet it was pulled from the line as a sample for maybe checking quality or other issue. and then put back on the line when done
That's nice. The cab on our '51 F-1 was almost rust free, just a small spot at the bottom of the left rear quarter. The doors were a different story, we had to replace the outer skin (about 6 inches high) at the bottom of each. The firewall had been butchered, when some previous owner installed an after-market Sears hot water heater... We fixed that as well.