Pivot Pin
Are you looking on the bottom of the keel or on the sides? The usual routine for O'day centerboards on the 80's boats is that there are two small plates on the bottom, adjacent to the centerboard slot. These plates retain fiberglass "wedges" which hold the plastic pivot pin up inside the slot. The removal and installation of the centerboard assembly is all done from below. I think it is a pretty slick design since the only thru-hull penetration is a small tube for the pendant.