Generally its the cylinder head or intake manifold...depending on the engine.
You will have to get that from the dealer.
The Thermostat is located at the low side radiator hole housing ( one end of the hole is connect from the radiator and the other end is connect to the housing
Depends on the year. Follow the top radiator hose to the engine. It will connect to the thermostat housing. The thermostat sits inside the housing.
If you follow the lower radiater hose it will connect to the thermostat housing. Remove the 2 - 10mm bolts on the housing and it will reveal the thermostat.
The hose coming from the thermostat housing connects to the upper part of the radiator and allows coolant to flow into the engine...
On the top/front of the block, there is a plastic housing that the 2 top hoses connect into. You have to take that plastic housing off and the thermostat is in there.
Look for the upper radiator hose. The hose will go from the radiator to the top front of the engine. The hose will connect to the engine through the thermostat outlet housing. The thermostat is located under the thermostat outlet housing.
Follow the Upper radiator hose on the driver side of the vehicle. It will connect to the Thermostat Housing attached to the motor. Unblot that housing from the block and your thermostat sits inside. You might have an issue with removing the housing do to the exhaust connecting pipe. Hopefully not :) This is on the 3100 series 3.1L
On a 1994 Ford Aerostar : Follow the TOP radiator hose from the radiator It will connect to the engine cooling thermostat housing The thermostat is INSIDE the housing * on the 4.0L V6 engine the hose actually connects to a metal pipe which is part of the thermostat housing
There is a thick radiator hose coming from the right hand side of the radiator at the top, follow that hose from the radiator towards the engine. I will connect to the thermostat housing, it has two bolts.
Follow upper radiator hose to engine should connect to a housing secured by 2 or 3 bolts--thermostat inside
Follow top radiator hose to were it connect to head. Remove 4 bolts and thermostat is there. Maybe 2 of them.