Rudder Hardware Timeline

[Dsoc]

Education Time

I am working on restoration of an early 60s Sunfish. Living and learning. The Rudder Hardware has 2 styles for the bronze set ups.
The one on the left has screw holes on the outside and is cut out for the rudder bolt. The one on the right has no cut out and has the screw holes inward. Hidden beneath the spring-plate.
Obviously the one on the right is older version. I cannot find anywhere dating the 2 different versions. Any help with this?

 

[signal charlie]

The one on the left is for the wooden Sailfish and Sunfish, the screw holes are for wood screws that screw into the transom. On the wooden boats the carriage bolt goes through the transom.

So I'd say the one on the left is the older horizontal hinge plate, also because it does not have the Patent Number that late fittings have.