METCO Crank Pulley Ring (Ring Only) 1999-2004 Lightning, 2003-2004 Mustang Cobra Our crank pulley rings are designed for use with our Metco Motorsports Interchangeable Crank Pulley Kit offered for the supercharged Lightning truck and the supercharged Mustang Cobra. These crank pulley rings are precision-machined from billet aluminum and then black-anodized for good looks and long-lasting surface protection. If you already have the Interchangeable Crank Pulley Kit on your vehicle, one of these crank pulley rings is all that is needed to change your boost level.