Sierra 18-1222 Thermostat Diaphragm Gasket - V4/V6 Loop Charge The Sierra 18-1222 Thermostat Diaphragm Gasket is interchangeable with the following: GLM 46130, Evinrude/Johnson 394408. Each Sierra product meets or exceeds the original equipment part it replaces. Sierra Thermostat Diaphragm Gasket Meets or exceeds the original equipment quality Sierra part number: 18-1222 Interchangeable with the following: GLM 46130, Evinrude/Johnson 394408