Examine the lens configuration first—sealed beam units indicate post-1940 manufacture, while separate bulb housings with ornate brass or nickel-plated reflectors signal pre-war craftsmanship. Look for manufacturer stampings on the rim or reflector housing, as companies like Guide, Dietz, and C.M. Hall produced distinctive designs that help pinpoint a vehicle’s production era within a few years.
Study the mounting style to understand engineering evolution across decades. Vintage automobiles from the brass era (1896-1915) featured acetylene or carbide lamps mounted on separate brackets, while cars from the 1920s transitioned …