There isn't one.
The system is designed to use the recovery tank on the driver side. There is a cap on the recovery tank and you check the level there and add coolant there.
On a 1993 Lincoln Town Car : The threaded cap on the engine coolant reservoir is the pressure cap / radiator cap
On a Lincoln LS : The engine coolant reservoir is located in the engine compartment , on the drivers side , near the firewall ( I believe it has a thread on cap , which would be the pressure cap / radiator cap )
On a 2002 Lincoln LS : The degas bottle ( engine coolant reservoir with the pressure cap / radiator cap screwed on the top ) is located in the engine compartment , near the firewall , on the drivers side of the engine compartment ( you will see the " cap " through a hole in a piece of " trim "
On a 2002 Lincoln LS : The engine coolant reservoir has the pressure cap / radiator cap screwed on top of it , so it is called a degas bottle * it is located in the engine compartment , on the drivers side , near the firewall ( there is a hole through the " trim " to gain access to the cap )
It is located on top of a plastic recovery tank located by the side of the radiator. The radiator itself won't have one.
On a 1997 Lincoln Continental : The thread on cap on the engine coolant reservoir is the radiator cap / pressure cap according to one of Fords websites , it is Motorcraft part number ( RS-85 ) a 16 PSI cap
On a 2003 Lincoln Aviator : The thread on cap on the engine coolant reservoir is the pressure cap / radiator cap
On a 1998 Lincoln Navigator : The thread on cap on the engine coolant reservoir is the pressure cap / radiator cap
On a 1995 Lincoln Continental : 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
There is no actual "radiator cap" due to the fact you have DexCool and an overflow with a pressure vent cap on it already. That is where you fill it up anyway....
The thread on cap for your engine coolant reservoir is the pressure cap / radiator cap ( the engine coolant reservoir is located on the drivers side of the engine compartment , near the firewall )