This appears to be the original fixed rudder, modified to kick-up. The Factory Optional kick-up rudder looks similar but has aluminum cheeks that extend up to the top of the rudder. Profile seems to be the same as the original fixed rudder, but construction is wood and aluminum instead of fiberglass w/foam-core. Here are some pictures of the factory-optional kick-up rudder, I received these from an O'DAY 20 owner.
BTW: All O'DAY 20's were built as Keel/CB boats as far as I know, and the standard rudder was fixed, not kick-up. I'm not sure why O'Day didn't make the Kick-up rudder standard from the start like on the 192 and 222.