It would be best to locate service manual for an engine with diagrams, showing parts.
However, most likely you have zinc somewhere on a heat exchanger. Iím not familiar with your engine. Just look at the heat exchanger and locate a bolt which makes no sense. It is something sticking on a side without apparent reason. Unscrew it, most likely there is pencil type zinc screwed to inside of this bolt.
I hope someone with knowledge of the engine will prove me wrong