How do you change the thermostat on Ford Transit 2.5 diesel?

To change the thermostat on a Ford Transit 2.5 diesel, first ensure the engine is cool and disconnect the battery for safety. Drain the coolant and remove the thermostat housing, typically secured by bolts. Replace the old thermostat with a new one, ensuring the rubber gasket is in good condition or replaced as needed. Reassemble the housing, refill the coolant, and reconnect the battery.