I want to install a monitoring system for my fuel tanks (2) and water tanks (2). I was looking at the one by Snake River Engineering but it requires a 1 1/2" hole be cut in the top of my fuel tanks for the sender. First I don't know what you could use to cut a hole in the cast iron tanks and second both tanks are full so I'm not sure there's anyway to do that safely. There is currently a dip stick that screws into a threaded extension on top of the tank. This threaded extension appears to be about 3/4". I was hoping to find some sort of sending unit that would not require cutting a new hole. My water tanks are stainless and in this case the sending unit requires a threaded 1" hole in the top. The top of my tank isn't thick enough to thread. Does anyone know of sending units for fuel and water that require small openings in the top of the tanks? TIA Mike Coble "Twocan"