Help! Old school question, same era as the bic wing, had multiple notches for the centerboard pin, D1 board. I think it was called the Lightning? Don't think f2 existed yet. Thick for a D1, but not thick enough to be a D2. You could really balance the thing, but it was fiddly. A beast! Images if possible? I can't think of the right question to ask the cloud. For the last 2 hours at least..

Ah! Found it- Magnum sailboards- can't post a pic

interesting centerboard adjustment system- google it