Sierra International 18-3899 Water Cover Gasket The Sierra 18-3899 Water Cover Gasket is interchangeable with the following: GLM 33700, Evinrude/Johnson 327674. Each Sierra product meets or exceeds the original equipment part it replaces. Sierra Water Cover Gasket Meets or exceeds the original equipment quality Sierra part number: 18-3899 Interchangeable with the following: GLM 33700, Evinrude/Johnson 327674