MTD Pulley Kit No. 753-0518. This is an original mtd part that includes the pulley, bearing, shoulder bolt and assiciated hardware. Replaces mtd part number 7530518.
MTD Idler Pulley Kit No. 753-08171. This is a quality aftermarket part. Inside Diameter 3/8, Outside diameter 4 7/8, width is 1" Replaces MTD part numbers 753-08171, 756-04129, 753-08068, 756-04129B, 753-04129C and Toro part number 112-0314.