On the reservoir towards the rear of the engine compartment, passenger side. You will see the plastic reservoir sitting on top of the wheel well.
On a 2001 Mercury Sable : The thread on cap on the engine coolant reservoir ( located in your engine compartment , on the passenger side of the engine compartment ) is the pressure cap / radiator cap
On the expansion tank, on the right fender wall.
You fill it though the resivoir cap
The 2001 Windstar has no radiator cap. It has an antifreeze bottle.
The radiator cap is located on top of the radiator.
On the coolant recovery tank
On a 2001 Ford Expedition : The thread on cap on your engine coolant reservoir is the pressure cap / radiator cap
On a 2001 Lincoln Navigator : The thread on cap on the engine coolant reservoir is the pressure cap / radiator cap
On a 2001 Ford Focus : The thread on cap on your engine coolant reservoir is the pressure cap / radiator cap
On a 2001 Monte Carlo it is located on the radiator just below the radiator cap.
The thread on cap on your engine coolant reservoir is your pressure cap / radiator cap
On a 2004 Ford Freestar : The thread on cap on the engine coolant reservoir is the pressure cap / radiator cap