The heater core is a pain for sure especially with AC. I am doing mine right now. I go to Advance Auto to pick up the core. I have used in past and they have 3 year warranty.
It is probably the worst job on the whole car but anyone can do it. You do have to take the dash loose and move it back to get the heater box out.
Be sure and take the drain hose off before you do anything else. It is also much easier if you remove both seats.
If you do not take the whole dash out there are a few wires that are a real pain to get out. The center part of the heater box is where the blower is and there are connectors to it and a ground wire screwed to the cowl.
It is a good time to review condition of the cowl also. With the box out you can use mirror and look into the cowl from the opening to the heater. I reach up through the hole and use a paint brush to apply POR after I clean as best I can then apply body sealer. It is guaranteed there is a leak there almost always. Look for any mice nests in the cowl also on both sides. The AC car does not have an opening on the driver side but mice love to build there.
You will also need a foam kit to replace all the foam in the heater box on the doors and seals. Go to the West Coast Cougar site and watch video on how to repair. You also might need to order the foam seal the goes around the heater core and AC tubes going through the firewall. Don or any Mustang supply usually has them.
There are two vacuum motors on the box that you need to test with a vacuum pump.
Also when you get your new heater core do air test it under water with about 15 lbs. of pressure. I have had two bad out of the box in past and one was NOS Ford.
I always add the 1/4" wire mesh between the foam seal at the cowl.
There are not that many fasteners holding the dash but if you remove the whole dash you have to unplug all the wire harness which takes time and is a pain.
I have a two post lift and do most of the removal with the car on the lift raised so I stand beside the car instead of having to lay in the floor.
Either pull your carpet out or protect with plastic the smell of antifreeze never seems to go away.
So I am off to get my heater core in a bit.
If you have not already change the AC over to new refrigerant good time to do also. Replace the dryer filter and change the lube in the compressor and of course the new green O-rings.
I am having to do the brake booster so I am burnt out on the tough Mustang repairs.
Some pics of past one I did.
It is not a job you do in one weekend usually. You have lots of cleaning to do and if your case looks bad you can clean and spray with satin clear to make it look new again.
The foam kits look nothing like the original much less dense but all you can get. Can clean all the ducts and blower housing makes air smell better.
upload photos online
