The AD trucks didn't leave the factory with turn signals until 1954. There was a after market turn signal kit that consist of a lever that clamped to the steering column, two lights for the front and rear. These kits were often installed by dealerships. I converted my turn signals on my 53 to work with the front parking lights and the tail lights with a toggle switch under the dash, I don't like that lever clamped to the steering column.
In the days when there were no turn signals, the arm out the window gave the signal... straight out was for a left turn, arm bent up from the elbow was for a right turn and the arm hanging down by the door was slowing down or stopping.
