How do you install a thermostat for a Mazda B2000?

locate the casting that contains the thermostat and separate it's cover. the old unit should be observed while it is in place in order that it's replacement is installed right side up. any old gasket material that may be stuck on the castings needs to be removed and the seal surfaces trued. follow the upper radiator hose to the engine and you will locate the casting that the thermostat is housed in.