Lower Unit Seal Kit | Sierra 18-2635 Sierra Lower Unit Seal Kit | Sierra 18-2635 Lower Unit Seal Kit Contains seal 18-0500; gasket, lower wear plate 18-0622; seal 18-2051; seal 18-2052; washer 18-2945; o-ring 18-7168; o-ring 18-7173; o-ring 18-7950 Replaces Mercury 26-814669A2 Replaces Mallory 9-74204