Yup, and the oil gauge sender has to tap into oil pressure like off the lifter gallery or the mains. The two standard locations are at the oil filter housing, and below the distributor. When they introduced the electric choke they tapped into the block by the timing cover for that switch, and by switch I mean an "on/off" type that only knows if there is at least 5 lbs of pressure or none at all. Years ago the coolant sender was in the intake water crossover, but in the head gives a better picture of engine temps. And there are also two types of coolant senders, either for gauges or idiot lights.
