Stainless Steel Raised Countersunk Screw Kit for the Blower Wheel  Cover. The M6 x 30 are  located at the top of the housing and and the M6 x 40 are  located at the bottom of the housing and 2 of each are required per engine. The bottom screws are longer than the top screws as the fuel and the engine breather overflow pipe brackets fix to these screws. You can buy these screws individually if required Part No 1912/1 and 1913/1