I have one (1) 'Intake Manifold Thermostat' in my parts bin (PN 14100-E8850).  As you probably know, this valve is NLA from Nissan and appears to be NLA from all the Z specialty suppliers too.  Its job is to control the flow of coolant through the intake manifold heating cavities (which also duct out to the carb bodies for 1972-73 models).  I expect that it's arranged to work the opposite of the regular coolant thermostat:  i.e. it operates open when cold, then closes off flow once the co