SmithLakeChevy,

That is a rare find.

Since the previous owner wacked off the turn signal switch ribbon wire, you can find one HERE

Does the lower portion of your steering column have the ribbon/horn wire hole cover?
If not, maybe the previous owner still has the cover & screw.

Here is Tim Lederman's page that has the 1954 - 1955-1st series Installation Instructions for Directional Signals on
Carryall Suburban, Panel, and Canopy Express Trucks.
http://1954advance-design.com/DirectionalSignalsInstall.htm

The Sub & Panel truck turn signal rear wiring is different from the pick-up truck rear wiring.
http://1954advance-design.com/Documents/Signal%20Install%2012.pdf