I know several shops that did more than one 8 3/4 and nine inch Fords back brace by stitch welding 1/2 to 1 inch at a time on the top of the left side first and then did the bottom right side next and switch back and forth letting each side cool for several minutes before coming back to the same side. They used a mig machine(wire welder) I don't know what diameter wire or heat setting but only one of there jobs warped the rear end housing due to getting in a hurry