[chris vickery]

When I replicated the rear wall on my 12 cab, I made my piece of sheet and test fit before welding.
The folded over end, I broke first and clamped into place. I then rolled the sheet around the first corner, clamping as I went. I worked it to the other end, up around the corner to the front. I then marked it where it met the edge. I removed the sheet and added the required amount to the marked line I made on the second edge. I then boke this 90deg. So, I essential had a piece of sheet metal which was the correct lenght with breaks on both ends.
I then refit this to make sure it was OK.
As mentioned Jordan, I did start from the center and worked back and forth towards each end. I replicated spots welds only where they were supposed to be, which included along the cross bracing at the rear.
My main mistake which led to some difficulty was the fact that I used 16g instead of 18g. In the end a very good rear panel.
If you notice on original panels, the spot welds do show up. Thats they way they were made, quick and dirty.
Keep up the good work!