Where is the thermostat located in a 1986 Nissan 720 Z24 pickup?

The thermostat is located on the passenger side of the engine. It you follow the top radiator hose to the engine, it is clamped to a housing. The thermostat is inside this housing. The housing is bolted to the engine block. There is a gasket to seal between the two parts. If you remove the housing, the thermostat just drops out.