Cummins ISF2.8/ISF3.8 Thermostat 5337966 Parts Catalogue Ref No. Part Name Part No. Required 1 Thermostat 5337966 1 Above is the introduction of the Cummins 5337966 Thermostat, while if you need any other Cummins spare parts or complete Cummins engine, Please further consult our sales.