What is this steering wheel?

Now, it's starting to make sense. In your first picture, the metal ring was turned upside down. The back of the vinyl pad has those tabs that hook underneath the tabs on the metal ring. Take a look at my close-up pic on page one of this thread and you can see the horn switch we have. It seems to have an integral metal fixture to hold a different style of pad (looks just like the stock one on my son's '74 Dart).

It does have the three mounting screws, so I might could modify this horn switch by removing the raised metal fixture. However, I would really like to avoid that if possible and get the correct switch. Anyone have an extra lying around?

Back to the Plymouth emblem...
It appears to be embedded in an acrylic disk. Does it just simply press-fit into the hole in the horn pad? Anyone have an extra lying around?

Thanks, guys, we're making progress.