Huh??? The gray wire is molded into the end of the cable along with the direct power to the starter motor. The gray then splits out in the middle of the cable assy to hit the relay. Then the small red hooks to that relay also, different terminal, and rejoins the cable assy for the rest of the distance to the battery. i.e. - the relay is a relative midpoint between battery and starter and controls application of battery power to the starter. You HAVE to have something similar in any factory type configuration. Now if this is a track only car with a starter pushbutton on the dash, the previous does not apply. Also not applicable if it's a 1940's vintage auto with the starter button on the floorboards, in that case the gray and red would go to the two terminals on the floor button.