Its hard to believe i know but most v6 and v8 engines still being produced for the Marine industry have raw water cooling(salt water running around head and block).The diesels run heat exchangers and the annode you have been given is probably an orbitrade zink annode that fits one of those.The raw water runs around the heat exchanger whilst normal coolant runs round the engine.I cant really see the point in fitting in a rad a good coolant does a pretty good job.
Em(Old salty dog)
