Your boat is fresh water cooled by the F indication in your description. That means you have an anti freeze circuit. That also means no saltwater through the block which is a really great thing. If you look at your manual you will see the dead bolts for where you "should have a zinc" in your engine block. That being said, some say you can have a zinc in your heat exchanger housing. I do not prescribe to this theory. The other zincs are on the end of your prop shaft ( tip of the prop) and one on the prop shaft itself(collar). You occasionally fiind a button zinc on the strut.
So there ya have it...
Good sailing!
You can purchase them at any chandlery or you can do what say "most " of us do and that is hire a diver to clean your hull monthly and monitor and change your zincs as needed.(buck a foot in SAN) They get them in bulk. The savings on bottom paint freshening alone is worth the cost IMHO(5 years out of my last botton job).
Oh yeah, if you dont have a galvonic isolator, you should consider. Will save you from the "hot boats" around you. And from yourself.