How do you replace the thermostat located on a 1988 Ford F-150?

To replace the thermostat on a 1988 Ford F-150, first ensure the engine is cool and disconnect the negative battery cable. Drain the coolant from the radiator, then remove the upper radiator hose from the thermostat housing. Unbolt the thermostat housing, take out the old thermostat, and clean the mating surfaces. Install the new thermostat, reattach the housing, reconnect the hose, refill the coolant, and reconnect the battery.