Mercruiser Complete Water Pump Repair Kit For MR/Alpha One MR / Alpha One (1984-1990) Includes: Upper & Lower Housing, Wear Plate, Impeller, Gaskets, & O-Rings Replaces : O.E.M no. 46-44292A4 Sierra no. 18-3320 no. 12120 Fits: Mercruiser Alpha One/MR 1984-1990.Sierra Part Number: 18-3320; Mercury Part Number: 46-44292A4 Color of components (housings, gaskets, ect.) may vary based on manufacturing processes. Free Tech Support by Calling 1(800) Fix-Boat or 1(800) 349-2628 Parts are made to replace factory components. Not OEM.