Well, The old girl isn't flopping around any longer. I braced, and braced, braced some more, checked it for square, level, braced it some more, checked it and then left it for a couple days. I was rewiring my dad's old skid steer! Rechecked it, and then checked it again. I don't know what I was waiting for. I was nervous, but it was too late now. Let's weld her up. I stitched it up with about 3" welds to help keep the heat down. I jumped back and forth from left to right. Inside to outside. Then I left it for another day and tackled dressing the welds today. I have a couple tiny spots I want to readdress with my welder & grinder for appearance, but it went very well and it sure seems short now! It doesn't seem too short when you're right beside it. You think, "Hmmm, is that a shortbox?"
Step back 20ft and, "Yup, it's a short box!"
I am happy with how it's gone so far. I rechecked my square and level after it was solid. I am happy to report that from front to back diagonally it is out 1/16". I'd call that good enough! I removed the cab mounts and the rivets from the manual transmission mount and will relocate the cab mount and install an automatic mount. I still have to brace the inside of the frame rail but this little adventure has gone well so far.
1970 Chevrolet C10 Grandpa's -- My first truck -- In progress to shiny Follow the build in the Project Journal 1950 Chevrolet 1-Ton Dually "Ole Red Girl" In the Stovebolt Gallery More pictures here 1951 GMC 9430 1 ton dually--Shiny! | 1972 Chevrolet C20- Rusty- the puzzle box lid for the C10 | 1962 AMC Rambler American- my wife's Parts trucks- 1951 GMC 9300 | 1951-GMC 9430 | 1951- Chevrolet 1300