1939 plymouth headlight rings

Answer 1

The 1939 Plymouth (like most 1939 vehicles) was equiped with "shaped" headlamp lens'. They were a square shape and for the first time were flush mounted in the fender.
   1939 was the last year of the non sealed beam bulb. In 1940 the sealed beam headlamp bulb was released on most models and were superior in lumination. As a result there were many retrofit kits that allowed older vehicles to be equiped with sealed beam bulbs. These kits were installed on many 1939 Plymouths and that is the reason that some cars are missing  the original "squarish" headlamp doors and lens. Hope that helps.....