?

These are the rudder head fittings (quadrants) attached to the port rudder on my Lagoon 410.
It appears that corrosive sea water leaked through the emergency tiller access through the hatch cover directly above these fittings. The corrosion is very deep into the galvanized steel fittings. Where can I get replacements for both the upper quadrant and the lower autopilot quadrant? Also are these somehow keyed into the rudder shafts or just tightly clamped around the posts.
Byrne Falke on “Spray”