Visual inspection will do nothing as it is impossible to see fatigue cracks with the naked eye when they are in the early stages of forming. In one of my previous jobs we used to use a very low viscosity fluorescent crack detection fluid which we sprayed onto the suspected area of the cracks, then wiped it clean and covered the area with white crack detection powder. The fluid will have cappilaried into the previously invisible cracks and the white powder would show up any crack present. Whether a chassis is cracked or not I really doubt the ability of this new bolt in support to prevent any existing cracks (as yet invisible) from getting worse or for new cracks forming somewhere else, given that the old chassis's must have been produced from old bean cans.
