The top lights are red emergency lights that were added in the 1970's. The lights below are just single element brake lights. There are no turn signels.

Is there a way to convert the lights to parking/brake/turnsignels?

Plus the Chevy Duty catalog shows a different type of 1951 rear parking light/brake in the catalog. The round looking ones on the truck (in photo) look like the 1954 ones shown in the Chevy Duty catalog.

I'll replace them with the correct ones but I waqnt you all's option before I order the other ones. What do you think? Am I just wrong about the lights?