The data Im providing is from a Dearborn built M-code Mach 1 built 12/69, 4-speed non ac. The pulley is 66MM or 2-5/8'' diameter measured at outer edge. The number is C5AF10A352-K . The number is located on the backside facing the ALT housing. The front of pulley has no numbers but alot of small marks near the hub where it was pressed together.