Original Thermostat for Cummins 6bt5.9/ISBe5.9/6.7l-24valves- 5271639/ 5319249. This thermostat is the perfect replacement for your Cummins engine. Made specifically for the 6bt5.9, ISBe5.9 and 6.7l 24-valve engines, this thermostat is a genuine Cummins part and comes with a manufacturer part number of 5345973. The reference OE/OEM numbers for this thermostat are 5319249 and 5271639, ensuring that you get the right part for your engine. It is a reliable and durable part that will keep your engine running smoothly and efficiently. Get this original thermostat now and keep your Cummins engine in top shape!