I actually did this myself on my 99 a couple of weeks ago, and never having done it before, I can tell you that it's not too difficult, just time consuming. I wouldn't recommend doing this if you aren't mechanically inclined. I didn't actually totally remove my dash - I just removed enough to be able to pull out the ac/heater housing. I removed all of the bolts for the dash along the windshield, the passenger side airbag, the glove box, the airbag control module, the cup holder, and most of the trim around the dash , like the bezel and the trim around the glove box. I also removed the bolts that secured the dash to the sides of the frame. There is one nut, though, that is kinda tricky to reach. It's on the passenger side, right next to the frame, straight up from the floor. It took me awhile to find that one! On the drivers side, I unhooked the e-break release lever, took the side bolt out, and loosed up the nuts holding the steering column on. I also removed the instrument panel, but I'm not sure if that is totally necessary. I also took the screws out that held the ac controls in place. Again, not sure if that was necessary, but did it anyway. There's also a bracket that's behind the airbag control module on the floor that needs to be removed. Then in the engine compartment, I detached both of the ac lines at the accumulator - make sure you have a quick connect tool to do that. Also, plug the lines to the accumulator so they don't get any dirt or moisture in there. You also have to disconnect the heater hoses, detach the pcm (all you have to do is take out the three screws holding it on-don't pull out the plugs) and disconnect the accumulator from the firewall. After you remove that nut and disconnect the ac lines, you should be able to move the accumulator out of the way. Now just slide out the metal plate that's behind the pcm to get to the nuts holding the ac/heater housing in. Remove those three nuts, plus one more that's right in the middle of the firewall to the right of the heater hoses. I had to remove my air intake to get to it. That should be all in the engine compartment. There's two more nuts that have to be removed to get the housing out. They're in the cab, on the passenger side. Just follow a grounding strap from the heater lines to the stud. The strap is attached between the two nuts. Remove the first nut, then the strap, and then the last nut. After that the housing should be ready to come out after you have pulled the dash out far enough. Remember to remove the vacuum lines and be sure to remember where they attach. There will be four of them. Also, you may have to disconnect the antenna. Ok-that should be everything to get it out. After it's out, just take out all of the screws holding the housing together and pull the two sides apart. There will be the evaporator and heater core. Take out the old and put in the new. When you put the two halves of the housing back together, make sure you line up the blender door properly or it won't work right. And as they say, installation is the reversal of the removal! Just be sure when you put the housing back in the truck, you line up the vent and defrost outlets with the end of the ac/heater housing. The ac/heater housing lines up to the outlets at the middle of the dash. I failed to do this, and now I have no defrost on my passenger side. I might fix it some day. Some things to remember are labeling where every vacuum line, nut, bolt, screw etc goes. And be sure to take it to a mechanic to have them evacuate and charge the ac lines. You could do that yourself if you have a vacuum pump and manifold gauges. I'm sure there's some things I forgot to mention, but hopefully this should get you started. Just ask if you have any questions. Good luck!!