I got to work on this project today. It looks to me like this cab had a lot of work done some years ago. The roof skin appears to be new(ish). It was brazed instead of spot welded. First I cut off the entire drip rail right up close to the skin. Then I cut around the entire roof as close to the drip rail as possible. The roof skin came off easy after battling the A pillar to inner skin area.
I used a flap wheel to grind the edge where inner and outer roof seams met. Use a flathead to pry just a little to pop the brazed areas.
All together it took me 2 hours to get the roof skin off. No spot weld cutter holes or other damage.
I wanted to do the whole outer skin from rear seam to front. But the rear seam area was rusty. So now my plan is to spot weld a 1" wide strip of sheet metal to the underside of the cab light skin. I'll slide it in place, with the panel adhesive applied. Use Tek screws to join the new and old skins at my cut. Let it cure, then tig the seam carefully to avoid warping it.
The only problem I see it trying to weld up next to the panel adhesive.
