Posting some photos of what you have might help. '68 never had a "tuff" wheel, so, I'm not sure what parts you're trying to mate together. Aftermarket wheels were notorious for not having a good horn connection.
Post #1, It is a aftermarket steering wheel and a OE Tuff Wheel adapter. The steering wheel is identical to a Mopar Tuff wheel.
Post #2, photo of an OE Tuff Wheel adapter
