I am thinking about moving from the old to new rudder style. If I pick up a used new style rudder will it fit into a new gudgeon? I guess what I'm asking is has there been any evolution in the design of the new rudder system over time?
It will fit. The only new evolution is the cheeks changed from aluminum to plastic, and the rudder itself changed from wood to plastic. Any of the new style rudders will work with the new style gudgeon.