4-108 has the heat exchanger
mounted at the flywheel end of the motor
. There is a zink on the left side of the heat exchanger
facing down. It is conveniently placed so that when you remove the old zink the salt water
in the exchanger runs all over the engine
There is another model of 4-108 that has a Bowman heat exchanger which is mounted under the header tank. I'm not sure where the zink is located on that one.