The “bullet” lights were used as dealer-installed turn signals until ’54, when the column-integrated turn signals were introduced. The ’54 turn signals could have been factory or dealer installed.
There was also a service bulletin issued in ’48 to use a bullet light over the doors as a tail light if driving with the doors open.
Looking through a 1950 Chevrolet Truck Data Book and it had the accessory “bullet” lamps listed as dual-filament stop/tail lamps. The ’39 Chevy passenger car tail lamps were most likely single filament? We wonder if they were dual filament for all Advance Design years? (If you know drop us a line!)
Panel Truck, Canopy Express, and Suburbans all had the bullet sidelights located using the same template.
The template at the link is a pdf of a scan of an original template.
1947-1955 panel-body dual tail/stop template