One thing I would recommend, I this was first recommended to me by Vic Cook, Forum Member and sheet metal wizard! was to make a "Cardboard Template of the door openings, I.E. Pinch weld perimeter, Vic and Scott Duckworth had already done this, and Vic Passed his template onto me.
while I was replacing my floor pan sections, I braced the cab from front to back, and side to side "X" bracing. I had to remove and replace the entire rear cab support bracing because the rot extended past where the patch panels would weld in at. once I was sure everything was in it's place, I placed the card board template inside of the pinch weld perimeter and it was spot on.
Then I started tack welding everything and re-checking often as I went.
Someone once told me to start from the middle and work my way outward, seemed to work for me, cutting small sections of the rotten metal and exposing the bracing underneath helped me to fit everything better, you can never have enough of those butt weld clamps you get at Harbor freight, I think I had 30 of 'em, and still needed some even after that....I wish I had a good assortment of "Cleco's" (spring loaded clamps that install in a small hole you drill) those would have helped in a few circumstances, but otherwise, I did a pretty good job if I may say so.... in hindsight, I should have bought the entire once piece floor with the bracing, would have been a lot simpler.
Good Luck!
Ben Smith
