That is the recoil starter rope sheave from an American Kingfisher, sometime around 1990 the American health & safety people decided it was too dangerous for over 6 hp outboard owners to have motors that could be started when they were in gear.
So Seagull had to fit an "interruptive start mechanism" to a US spec Kingfishers as these were the only motor in the price book that was 6 hp or over.
If you have the American spec recoil cover it will have 2 threaded holes either side of the one that holds the guide pulley for the recoil rope.
I'm sure somewhere I've got some more of the components of this essential device if it's a "got to have item".
Make it idiot proof and someone will make a better idiot.