Thanks for the quick response, Wolfgang. I'm still trying to find someone from the Fiberfab "959" era that might recognize these unmarked wheels, and their unique center threaded stud attachment. The weren't offered with the 356 kit, but I persuaded them to allow me to get them. In the pic, it can be seen that the stud is threaded into a nut on the underside of the chrome extension at the wheel center; for the spinner to accept that stud into the center of the backside of the spinner.