Here is a complete (no lever/knob) 1954-56 tuck turn-signal unit.

http://www.classicparts.com/1954-56-Turnsignal-Cup-Assembly/productinfo/53-531A/

The 57-59 unit has different electrical connectors.

This knob/arm is described as being just like the original, but the knob is not as "sleek" as the original 54/55 knob.

http://www.classicparts.com/1954-59-Turnsignal-Lever-w_-Knob/productinfo/29-555/