This is correct. I have not seen one of the black wheels that has provisions for a horn. This first picture from my earlier post (#14) was from a black wheel. Just a blank cover plate on the backside, no contacts for the column, no connectors for a horn button. The horn button itself is more of a cover for the steering wheel hub, not an actual functioning button like on the chrome steering wheels.
The black steering wheel I have came off an '82 Mustang, which had the horn located on the turn signal stalk. No need for any of the horn guts to be located in the steering wheel, as they are all in the stalk/column.
OK, now that you mention that, I do remember some of those cars now. Always thought it was one of the dumbest ideas for horn placement.