CX-5; Left; FWD; From 5/1/13. A flat disc with a hole in the center that is placed under or between the Differential Housing Mount or related components to even out pressure as they are tightened. A knuckle used on a steering axle that has no additional components attached. From 05/01/2013. Differential Washer. Hub , Support. Spacer. Steering knuckle.