In episode 1 of season 10 "that's show biz" 10 minutes into the episode Potter tells Brandy Doyle, a stripper travelling with the USO, that "Everytime I watch a C-42 reving up I think about how you used to spin those tassels."

The text implies that there were many, certainlay more than one, C-42s and that they were still in frequent use by the military during the Korean conflict.

According to the National Museum of the U.S. Airforce, only one Douglas C-42 was ever built. Two C-39s were converted to similar configuration/use.

By 1945, long before the Korean conflict, all three airplanes had been sold to the private sector. Potter would not have seen any revving up...