I took my furnace and wall out of my 1955
. Most of what you are looking at is probably not going to be reused, so pulling it out in pieces is ok. The top of the walls and cabinetry is screwed into the inner shell and sometimes screws are well hidden but once the top is loosened the wall should slide out of the curved aluminum channel which is riveted to the inner skin.When taking walls out of my 55 Overlander. I just pulled out in pieces, walls I was not going to use. The furnace is screwed into it and also to the floor.
Hope that helps