In 1955 the option M164 was provided by Volkswagen for the USA market.
Volkswagen stopped using the central brake light on the decklid on 05-04-1957.
From now on they outfitted the buses with dual taillights who had the functions: tail/stop/direction indicator light. This is possible while the current of the brake light switch is running over the indicator switch.

Prior to this self cancelling switch, Volkswagen used the same switch as used for semaphore or direction indicated buses.(211953521)
The wiring diagram shows how a switch with 3 connectors is used.