That's the oil pressure sending unit. It's what drives the oil pressure gauge in the car.That’s what I thought but I didn’t want to assume anything. I got $500 for the Fi Tech unit. People were all over thing. Now I just have to decide on a carb. Decisions decisions! For some reason I’m drawn to holly and I don’t really know why. Anyway what is this on the back of the motor. It has a wire hooked up to it?View attachment 243746