Let me look in my barn and take a couple pictures - I think I have an extra rudder that has the lead weight like a Super Porpoise rudder, but I think it has a plastic rudder head. Not sure if it was from a knock-off sailboat, maybe?
Okay so I took a picture of both. My original Super Porpoise rudder on the left with the metal (aluminum?) rudder head.
The extra one I have is definitely a molded plastic rudder head, but it looks to be pretty much the same thing. It has a tiller, but not the retaining pin. Rudder appears to have a crack in it as well.
My rudder pin has a small stainless steel chain attaching it to my boat. Do you know if your rudder pin has always been attached to the rudder? Also, does your rudder pin have a hole in the tip for a cotter/retention pin of some type? I couldn't tell from your picture.