I apologize to everyone for my lack of perception.
I incorrectly believed that hotrodders had enough common sense to determine when metal was structurally damaged and required replacement.
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I don't do semi's either, but one of my regular customers (that I have built several cars for) owns a trucking company, and the KM is the best product they have found. They wouldn't use POR if it were free. POR won't stay on no matter how it is prepped.
I have looked at semi's at truck stops in my rust research.
Most 1/2 inch thick semi frames have LOTS of pits in them, and so do the axle housings, etc. Don't get the idea that the DOT is very strict about rust, they are not. One of my best friends is a cross country driver.