There are two areas of these cabs which you don't want lose integrity/dimension while replacing panels.
1) the "ring of death". That is all of the metal that makes up the opening where the door fits in. rocker panels at the bottom, hinge pillars, lock pillars, top of the cab. As long as you don't cut any of those parts, you won't need to brace the door openings.
2) the distance between the hinge pillars at floor level. New floor panel halves combined do not measure the same as the original floor. Kevin's angle iron brace is all you need to replace the floor. I suggest that you only work on one side of the floor at a time. This will allow you to remove half of the floor and one front cab support at a time without the entire front of the cab collapsing.
Carl
