1998 Ford Station Wagon core

Here is what I found for you.

Disconnect the negative battery cable.
Drain and recycle the engine coolant.
Remove the instrument panel. Refer to Body & Trim.
In the engine compartment, label and disconnect the heater hoses from the heater core.
Plug the opening on the heater core inlet and outlet tubes to prevent coolant from flowing out into the passenger compartment.
Remove the four retaining screws and remove the blend door actuator from the evaporator housing.
Remove the metal cover and disengage the spring from the heater core cover and remove the spring from the lever.
Gently depress the locking ramp and remove the lever from the secondary A/C air temperature control door.
Rotate the primary A/C temperature control door shaft down, then swing the metal link and remove the pin.
Remove the three heater core cover retaining screws and remove the heater core cover and seal from the evaporator housing.
Remove the heater core from the evaporator housing by pushing on the heater core tubes.

To install:

Transfer the foam seal to the new heater core.
Install the new core with seal into the evaporator housing.
Position the heater core cover and seal into position and install the three retaining screws.
Install the metal link over the pin on the primary A/C air temperature door lever.
Install the secondary A/C air temperature control door lever-to-secondary A/C air temperature control door end.
Engage the spring on the heater core cover and secondary A/C air temperature control door lever.
Install the blend door actuator.
Connect the heater hoses to the heater core.
Install the instrument panel. Refer to Body & Trim.
Connect the negative battery cable.
Fill and bleed the cooling system.