[71GMC_3/4T]

Yep, it's usually white or black plastic with a brass ring on it. There is a spring loaded thingy that contacts the underside of the "dish" that mounts to the wheel under the horn button cap.
If you short the wire that attaches to it, it should honk the horn, or at least click the relay. If the relay clicks, put the steering wheel back on. You're looking in the wrong place...