This is the factory thermostat housing located at the front of the cylinder head. They are used on 4.0s & 2.5s, they did have a couple variations explain below. These do come with the coolant sensor installed, unless you purchase with out it.
#1 1997-2006 Jeep 4.0 & 2.5 Engine - These are the ones used when Jeep went to OD2 systems. This Sensor tells the PCM the temperature which is then sent to the gauge cluster.
#2 1991-1996 Jeep 4.0 & 2.5 Engine - These are used in the models with one large bolt on plug at the PCM. It ONLY tells the PCM the temperature of the engine while another sensor runs the gauge cluster.
#3 1991-2006 This is a bare housing with no sensor at all installed. Jeep 4.0 - 2.5 - Could be used in older 4.2s to install a temp gauge or sensor.
#4 1987-1990 This is the same housing as above but with no threaded bung for sensors. These were used in the Renix Jeeps & Older 4.2 Engines.
