I broke it into a series of smaller jobs. If need be, I can expound on them. You'll need sockets (extensions and universal fittings), screwdrivers, and some patience. And some beer wouldn't hurt either.

Heater Plenum Replacement:

1) Remove Glovebox. There is one nut on the inside that holds the heater plenum in place. It is just below where the glove box is. Unplug the black/white vacuum line connector that is near this nut. You can wait till later, but the dash will make it a pain.

2) Remove Radio/Radio&Vent Bezel. Carefully unplug all the connectors from the 4x4 switch, foglight switch, etc.

3) Remove the Instrument cluster. Be sure to disconnect the battery before you do, because at this point, you are serious, and you probably don't want an airbag in the face. Take off all the panels below the steering column, the instrument cluster bezel, and the steering column cover. Unplug the connectors from the back of the cluster carefully, the circuit material is fragile.

4) Take off the fuse panel cover. (Needed to put something easy in). Unscrew the "ocrap" handles and pop the plastic trim pieces they hold on off. Take the front screw out of the door sill covers so that you can get the bottom trim piece out.

5) Pop off the defroster cover. Black piece of plastic where dash meets windshield.

6) Unbolt the dash. Start with the four nuts that hold the steering column to it. The steering column will now hang down and be a real PITA. Just rest it on the front of the seat. There are two large gold-colored bolts by the fuse panel, one on the passenger's side, and two above the steering column where the winshield meets the dash. There is one black bolt in a similar location on the passenger's side. There are two more smaller screws also in that area, above the radio bezel. There is also a screw below the dash, on the driver's side, that is holding a bracket from the dash to a location near the front of the tranny hump.

7) Get a friend, give him/her a beer while you explain that you are about to pull the dash forward. Have some jackstands on hand to be able to prop the dash up so it isn't resting on wires.

8) Pull the dash back and up. It should come, if not hold it (or prop with jackstands) and look for what it is hanging on. Gently unscrew/unplug it and be sure to document it. You'll probably need to unplug the vacuum lines from the heater plenum and the electrical connector from the actuator.

9) Now that the dash is hanging there, you are probably thinking, "what the heck am I doing?". Move to the engine bay and start attacking there. First take the two heater lines off the heater core. They are held in by hose clamps. Just use a pliers to clinch them, then pull the hoses off and point them upwards. Have several rags on hand. Put one under the two before pulling them off.

10) There are more nuts that hold the plenum in place. One is directly behind the engine, near the middle of the firewall, off on its own. It has only one nut on it. Two are on the side of the AC housing that mates to the hole in the plenum. These have one nut on the outside, and one behind the housing. Tricky, eh? You'll need to get the other nut off the fan housing before you can reach those. Once all the outer nuts are off, pull the entire assembly forward in the compartment. Now reach the inner nuts. There is one more nut holding the plenum in place behind and between the two sections of the fan/AC housing. Now that you have it pulled forward, this one should be accessible. Also don't forget the two inside nuts that were on the other two studs. You won't remove the plenum with these still on, trust me.

11) Be sure that you have taken the inside nut off and the vacuum lines that were mentioned in step 1. You could do this now, but the dash makes it a pain.

12) The plenum should now just pull back. Be careful not to let it lean forward and dump coolant out of the heater core onto the floor. I didn't spill any, but it was tight. Basically, I took the plenum out the hole between the door and the dash (which should now be suspended over the passenger's legs). There is a wire harness that will make it a pain. You could probably unplug this and save yourself the hassle, but I managed to gently get the plenum past it.

13) Once the plenum is out, have a beer you've done a good job. Swap the heater core from one plenum to the other (unless the new plenum has one, or you are replacing it). This will require cutting the foam insulation a bit so that you can get the lines out. No biggie. My used plenum came with it cut like that. Just take the 4~5 screws that hold the heater core access hatch down, take it off, and pull the core straight up.

14) Put the new plenum in the way the old one came out. Line it up with the holes and have your beer-bribed friend start one or two of the nuts on from the engine bay side. Go around and check that he/she put them on right, then put the others on. Don't forget the inside ones (2 nuts on one post) or the one that is behind the housing. Reattach the Heater core lines. Get it all together and check to make sure it all looks good.

15) Now start reattaching the dash. It's basically the opposite of how it came out. Just try to get the dash placed on there properly so that air blows to the correct places. Put in all screws and reattach any connections you took out. Remember the nut on the plenum below the glove box, the vacuum lines near that (black&white), the vacuum line connector on the plenum (multicolored), the actuator lines, etc. Don't forget the steering column too, unless you'd like your own version of "tilt steering".

16) Put in all the interior pieces and cluster, glovebox, radio/bezel. Give them all a good wipe down and vacuum before you do.

17) Reattach the battery, cautiosly fire up the car and test it out. Hopefully you'll have heat/AC now! Watch for Airbag warnings (did you plug everything back in that you unplugged?) and other little bugs.

-Jim