Application : Workhorse P30 Accessory Drive Belt Idler Pulley. 2004 Workhorse P30 Grooved Pulley; 76 mm O.D. Pulley; 17 mm I.D. Bearing; 28.7 mm Pulley Width; Position: Serpentine;. 2005 Workhorse P30 Grooved Pulley; 76 mm O.D. Pulley; 17 mm I.D. Bearing; 28.7 mm Pulley Width; Position: Serpentine;.