The 1954 truck steering column does have two holes/openings in it for the optional signal assembly (first year for this GM option).
hole near the top of the column for the signal wires to enter into the signal assembly "cup".
a hole on the lower right side of the column, just below the column-to-dash clamp (sorry about the quality of this photo).
The standard "cup" attaches to the bottom of the steering wheel via two screws.
The standard "cup" is removed and a signal switch-cancellor (cancelling cam) is screwed into the bottom of the steering wheel via the 2 two screws that had attached the standard "cup".
The RPO signal-assembly cup does not get screwed to anything (there are no attachment holes in the steering column) - there is a wedge with a tightening screw inside the RPO cup. The cup is position 1/8" below the steering wheel and
the wedge screw is tightened.
