It would seem to appear that if you see no other hardware (screws or rivets), that the bolt that holds the upper shroud tangs to the mast will also be the sole attachement of the masthead to the mast. My advice, when you call Rudy to order the Sheaves, ask him about how the masthead is secured. He should know. (You can order online using the web-site, but a call is often stil lworth it!)