I don't know if the trucks had illuminated bezels, but the cars did. Immediately behind the dash was a stand-off, about 1/2 inch deep, which had holes for the dash switches and another hole for the light bulb socket.
On my '55 car, the ignition switch spring rests against that 1/2 inch deep standoff.
Look at your other dash switches and see if they have stand-offs. If so, you must be missing one.