Another thanks to Michael for generating this very helpful document! Just saved myself a lot of money by doing the HC in my 2000 supercab. Probably took me over 12 hours but I took on a number of side-projects while I had the dash apart. Here are some additional words of advice:

1. As others have noted, for some model years (including 2000), there are (2) more screws hidden beneath pop-out covers near the very front of the dash.

2. I wound up breaking my antenna cover because I didn't understand how it was attached. Don't pry up on the plastic. Pry out on the two flat edges first. The clips are there, if you pry them straight up they will break off.

3. You can rent the hose-pulling tool from Autozone, but still expect to be frustrated. I actually replaced my hoses a couple months ago and knew that the hacksaw approach would be easier -- I certainly recommend it, especially if you are reusing the old hose clips.

4. As I had no assistant for this job, and a previous owner left a rat's nest of wires around the steering column from an aftermarket remote-entry, I found it easier (but still not required) to pull out the instrument panel before dropping the dash. This was originally because I was worried about damaging the panel or tearing unseen wires, but it also gave me a chance to dust off the gauges, replace a bad bulb, and repair a cold solder that made the odometer turn off sometimes.

5. Following the overwhelming advice on the forums, I tried to replace the blend door as well. The replacement from the neighborhood parts store (I believe it was a Doorman) now features metal reinforcement at its base which seems like a nice improvement.

Here's the problem there: the metal-reinforced part was slightly too large to fit in the original hole. I could force it in, but it definitely wasn't going to pivot with the motor. I could have reamed the plastic hole with a file or a knife, but not with the blend door motor installed. I decided not to bother; I was running out of weekend hours and didn't want to fumble the dash back into place to tackle the ducting and motor from below.

So my advice if you are planning to replace the blend door: Drop the ducts and blend door motor from below before you pull the dash onto the seat. Then you can ream out the hole from above if needed. Another benefit--you can check the door motor to make sure it didn't get wet.

 

Here is a good youtube video on doing the F150 heater core.

 

Have to give a big thanks for those directions Have a 99 5.4 that had a core that held for 4 years with some prestone sealer. Thought I would be nice and gave her a good chemical flush before fresh coolant this time and that must of scrubbed the plug out, and when it coolant fogged me the 2nd morning I flushed a couple of times and ran sealer again which worked. Needless to say I didn't realize it took out the actuator right away because all I was doing was flushing and bringin the Tstat open. No cold air and couldn't hear the door moving. Of course when I pulled the actuator down there was pieces of the door shaft droppin out and the actuator was dead.

So the choice was to spend the $80 plus bucks for the hack the plenum door repair, or $100 for the actuator, door, and core. Used the Doorman door with the metal band and it was only the very bottom of the pivot hole that need a quick fileing for smooth movement. Between this write up and all the videos the job went off without a hitch. Only had one screw left over and that was to the floor vents up in back, said screw it and wedged a chunk of rubber between the silver box and the vent assy. Hopefully another 120,000 miles till the next one