Sierra 18-2244 Drain Screw for Mercury and Mercruiser This Sierra 18-2244 Drain Screw is for use with the following Mercruiser I, R, MR, Alpha One, TR, TRS all OBs with 38-16 non-magnetic gear lube fill or vent screws. Includes 18-2945 Drain Screw Gasket Thread Size 38-16 Interchangeable with ChryslerForceUS Marine F40109 10-F50109 10-79953A2 10-79953 GLM 22420 Mallory 9-72650 Mercruiser Stern Drive 816610A2 816610A1 10-28634A1 10-28634 10-79953 10-79953A2 10-79953Q2 10-79953Q04 Mercury Marine