Hello and thank you for choosing Just Answer.
I am not sure if these picutres below are what you will be looking at. But the thermostat is located under the water outlet. If you follow the radiator hose from the radiator back you will see the water outlet, take it off and you will see the thermostat.
Remove the thermostat assembly retaining bolts
In some cases the hose may be left attached to the housing-note that the gasket is still attached to the housing. The gasket must be removed, the housing cleaned and a new gasket installed
Remove the thermostat from the engine-other models similar
Loosen the securing nuts, then remove the water outlet, gasket, and thermostat from the thermostat housing.
When installing the thermostat, always use a new gasket with sealer and make sure the thermostat spring is facing the inside of the engine. The water outlet housing on VG30i and VG30E engines has the letters UPR and an arrow embossed on the flange edge; they should always be pointing up. The KA24E, VG30i and VG30E engines have a jiggle valve on the thermostat which should always be facing up. Water outlet mounting screws should be tightened to 12-15 ft. lbs. (16-21 Nm) on all engines but the KA24E, which should be tightened to 5-6 ft. lbs. (7-8 Nm). Refill and check the coolant level.