This is an MTD add on part, 3/8" bore X 3" diameter A belt or the old fan belt idler pulley. Closes I could find was from Northern Tool, 3/8" X 2-5/8 V belt pulley. Took them 2 weeks to figure out they were out of stock and on back order. This idler provides tension on the fan only on a d600 Kubota diesel in a 1512 C C tractor. Everything I found is 5/8 bore X 3" V belt application. Possibly make a V belt pulley work, belt would ride deeper in the pulley but have plenty of adjustment. Anyone have any idea on where to look to find one would be appreciated.