Peter,

If you want dual indicator lamps, you will have to improvise. A single indicator lamp socket was standard on all 1954 trucks at the bottom of the speedometer dial (except for flat-faced cowl).

You say your set-up is the original style, here is a wiring diagram. The single indicator light is connected to the middle leg on the flasher (the black wire).

Another drawing, showing the flasher.

Color-codes original switch wiring.

Tim