My tach has been sticking at about 4k. Well today I was rummaging through some old boxes and found another cluster with a tach. So I removed it from the cluster. Before I install it I wanna be sure 1- its for 8cyl and 2- it works smoothly and accurately through the rpm range. I was thinking maybe first to test it off my current HEI tach terminal. What wires go where? iirc, the body is grounded, then there's these white and black wires on the back of the tach, are they 12v and tach terminal?