On mine (2011 36) the diesel feed for the heater is in the top of the fuel tank adjacent to the fuel gauge - I think becausue there was room and easy access there! A fresh hole was drilled in the tank and the feed pipe pushed in. It is sealed by a pinch together flexible rubber seal that is tighted and sealed from the outside of the tank. Mine started to seep a bit when we were in rougher seas, so needed some hylomar blue on it and to be reseated down. Now all fine.
