Regarding using up surplus previous model parts, in Australia, it is not uncommon to see a 1940 Ford Deluxe Fordor Sedan with 1939 Ford Teardrop Tail Lights, as per this example. Not that these cars are plentiful, as under 2000 1940 Ford Deluxe Fordor Sedans were sold in Australia, but over the last 40 years, I can recall seeing quite a few that came from the Factory like this. This issue is definitely not a one-off regarding this model.