I received a new 7 Blade RV tow plug for my 55 Safari.
The wiring on the new plug follows the RV Standard color code arrangement.
Although I cannot find a tow/running light wiring diagram for the 1955
Safari, I did find a wiring diagram for a 1963
The RV Standard color code matches the color code for the "63 Airstream.
I tested the continuity at each position/wire color with my Fluke meter.
Green - Running Lights/Tail Light at 1 o'clock
Red - Left Turn Brake at 3 0'clock
White- Ground at 5 0'clock
Blue - Electric Brake at 7 o'clock
Brown - Right Turn/Stop at 9 o'clock
Black- 12V + at 11 o'clock
Yellow - Backup Lights at center
My '55 Safari uses all blue wire inside the shell for the 12V tow/running lights.
There is only a single blue wire to each light fixture. The ground comes from the shell.
The electric brake wire is carried by a two wire shielded cable. I haven't torn up enough flooring yet to see the entire wiring layout for the electric brakes.