anode location

[CHW]

I have a 2004 Sea Ray with a 496 Magnum fresh water cooled engine. The owners manual mentions checking the condition of the sacrificial anode in the heat exchanger. I have looked the thing over thoroughly and cannot find any external attachment on the exchanger. Marina mechanics can't help. Anyone ever find out where this thing is located? The same was simple to find and replace on the exchanger of my Kohler generator.

Thanks