Remove all the screws you can see. Generally the tough part is a slow, steady "prying" with a 1" (or wider) putty knife, trying to loosen the agressive caulking between the sheet metal. Have your propane tank valve off and disconnect the LP line at the fitting going into the furnace regulator. Electrical plugs will simply disconnect. Once the outside cover is removed, look carefully around the base flange of sheet metal, especially in the corners, for small 1/4" hex head screws that hold the furnace into the sheet metal housing. You gotta remove those mounting screws so the furnace can be slid out. The rest of the disassembly is pretty straightforward. Suggest putting an old white bedsheet on your workbench to keep track of all the little screws and stuff.
Last Brave 2004 34D