This page
http://www.erareplicas.com/427/wheels.htm helps show the difference between true 6-pin drive hubs and the "next step down" at 5-pin. Bolt-on wheels are just like any other car. It's easy to mix up the two pin drive systems when giving advice on CC -- we had a thread not too long ago having to do with torquing drive pins and several of us (including me) did not notice that the poster had 5-pins and we were responding with 6-pin answers.
Of course, not all systems are the same between different Cobra makes, but those are the three basic wheel systems.