StayCoolPumps Impeller Kit Replaces Sierra 18-3276-1 New Impeller Kit , Includes Impeller , plug and O-ring Replaces: Sierra 18-3276-1 Replaces: Volvo Penta 21213660 , 3862465 , 3862567 , 21213650 , Fits Volvo Penta Gas Sterndrives 1999 to 2005 and other models. 3.0 , 4.3 , 5.0 , 5.7 , 7.4 , 8.1 Width 1-1/4" (31.5mm) . Diameter 2-1/4" (57mm) . 5/8 shaft 12 spline : The black rubber disc (spline plug) is not used in all applications and may not be needed.