Quicksilver - Aluminum Prop Nut Anode Fits Select Mercury Propellers and Outboard Engines 2-5/16" Diameter 809666T. Overview. Every boater knows that saltwater is both a playground and a challenge. The Quicksilver Aluminum Prop Nut Anode (Part Number 809666T) is built for those who respect both sides of that equation. It's one of those small but vital parts that quietly does its job, protecting your outboard or sterndrive from corrosion while you focus on what matters, smooth running, open water