Heater core in a 1998 Ford F-150 4X4 5.4

Here is what I was able to get for you. Let me know if it helps. I have attached pictures to help, but I have to be honest, it isn't a fun job.

Have a HVAC-trained, EPA-certified, automotive technician recover the air conditioning system refrigerant.
Drain and recycle the engine coolant.

Remove the driver's side quarter trim panel.
Detach the electrical connectors on the auxiliary air conditioning and heater assembly.
Disconnect the heater core hose couplings.
Remove the evaporator case drain hose.
Disconnect the auxiliary A/C evaporator lines.
Remove the pin-type retainer.
Remove the A/C outlet duct.
Remove the three bolts and remove the auxiliary air conditioning and heater assembly.
Remove the ten evaporator/heater core access cover retaining bolts and remove the evaporator/heater core access cover.
Remove the heater core. To install:
The installation is the reverse of the removal.
Have a MVAC-trained, EPA-certified, automotive technician recharge the air conditioning system.

Let me know if you have additional questions.
Joe