Gasket Riser Blank for Mercruiser 1983 and Up Closed Cooling Replaces 27-41811 Block off Riser Gasket used on Mercruiser V6 & V8 engines with center riser manifolds from 1983 & up. This is used when the manifolds are fresh water cooled. It fits Osco # 4354, Osco # 8503A & Barr # MC20-98502 risers Replaces: Mercury Quicksilver # 27-863725-1; Barr # MC47-27-41811; GLM # 30220; Sierra # 18-0672; Mallory # 9-61422
