3.0 LITER V6. Thermostat seal. A flat disc with a hole in the center that is placed under or between the Thermostat Housing or related components to even out pressure as they are tightened. Engine Coolant Thermostat Gasket. Engine Coolant Thermostat Housing Seal. O-Ring. Engine Coolant Thermostat Gasket. Engine Coolant Thermostat Housing Seal. Engine Coolant Thermostat Housing Washer. Thermostat o - ring. Thermostat seal. Thermostat unit gasket. Thermostat unit o - ring. Thermostat unit seal. Included with: Thermostat unit, Thermstat unit.