I am working on one of these as well. The complete ammonia unit can be removed as a unit, 8 bolts on the rear and the freezer unit will slide out the rear with the unit. Mine had cardboard insulation, 3 inches thick, but it comes out very easy. I am a little concerned with the wooden frame that separated the inside box from the outside and is what the door mounts to, not sure how to keep the hot element from overheating it and starting a fire. Once the insulation is removed, look over the outside box well, mime had what looks like roofing tar sealing the back and bottom to the sides. I used a propane torch and scraper to CAREFULLY heat and remove as much as I could. I plan on using 3 inch rock-wool for insulation, and building a box to drop the electric heating element below the floor about 8 to 10 inches to increase the size of the smoking cabinet. I have the pid and heater, just need to find time to get every thing put to gather. I will use Todd's wonderful invention to provide the smoke and flavor, with the mailbox mod. to house it.
Rednek, Great looking build, hope mine comes out looking that good.
Bud