Mercruiser Water Pump Repair Kit | Sierra 18-3317 Water pump kit includes base & housing for Mercruiser #1/R stern drives without flush screw in front of gear housing. Sierra Mercruiser water pump kit with base For Mercruiser #1 and R model stern drives without flush screw in front of gear housing from s/n 2763442-6854392 Includes housing and base Replaces Mercruiser 46-57234A8, 46-96148A8 Replaces Mallory 9-48305