Here are sources for both the plastic cap that Amel installed in leiu of the Autoprop zinc, and for the actual zinc-zinc for the Autoprop,including the H-6 that many SM's and 54's have.
They call the plastic cap a "plastic zinc" even though it is all plastic.
The source is King Propulsion in Virgina Beach, Virginia, USA tel. +1 757 962 9219
kingpropulsion dot com
About $36.00 US plus shipping for the H-6 Autoprop plastic cap with fasteners.
King Propulsion is a USA manufacturer's representative for Bruntons Autoprop so they also have the bearing rebuild kits. I have to commend Rod there because he also sells the O.E.M. zinc-zincs, but said he couldn't come anywhere near to matching the below source on pricing, and referred me to them.
For the "zinc-zinc" the source is
+1 978 842 9978
$19.53 US for the H-6 Autoprop zinc with fasteners.
They bill themselves as the zinc anode online superstore and have just about every kind of zinc imaginable, at good prices.
Wishing smooth sailing and endless broad reaches to all,
SM384 Sirena Azul