Well the big ones ( more common) are the Armstrong and Stainless Marine (both Aluminum) and then there is the Seamark (Potter Fiberglass bracket) Do a search for Brackets and you’ll find a lot more info……. Here’s a couple of links to start with a focus on the Seamark bracket……Look at the main page of Classic SeaCraft under links and goto the Hermco site for more info / pictures
http://www.classicseacraft.com/cgi-b...c;f=1;t=000112
http://www.classicseacraft.com/cgi-b...c;f=1;t=000340