I'm sure its posted somewhere in the forum, I just cant find it through the search engine. On 455 by oil filter/pump there is the oil sender for the dummy light on dash. but what is the sender on the back of the head for? I see two/three wires on it and I can't see them on the FSM wiring diagram for my model year. I am installing aftermarket gauges and I'm going to be using the senders for water and oil on the front of engine and top of intake. I'm just curious what the sender at back of head(left head as I'm standing in front of the car) is for.