OTTO Excavator Parts Yc 4Hf1 Thermostat Shell 8973727690 897372-7690 8-97372769-0 For Isuzu The OTTO Excavator Parts YC 4HF1 Thermostat Shell, with part number 8973727690, is a component designed for Isuzu engines. It serves as a housing for the thermostat, aiding in the regulation of engine temperature for optimal performance and efficiency.