Mercruiser 3/4" Water Intake Hose | Sierra 18-3602 Sierra 18-3602 Water Intake Hose Mercruiser 3/4 in. Water Intake Hose For Mercruiser MR, Alpha I, and Gen II model stern drives 3/4 in. diameter 13 7/8 in.length Replaces Mercruiser 32-4172533 Replaces Mallory 9-72003