IMO: First, setting on back is OK. Replacing a rocker and cab corner will not tweak the 6 sided box. Floor braces, depends on if you can keep the cube/box/cab supported by replacing one at a time. Cowl panel, not sure how much cutting you are doing. If you think you will be loosing the "cube" by cutting something you should brace door openings and floor and windshield opening possibly also depending on the cowl thing. I assume you means supports not floor pan. The pan gives much strength to the cube. If you are taking out/replacing the entire pan to get at the supports, then brace. The true answer comes from a 60-66 owner who has done it. Put this post in the 60-66 forum also.


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