Hi John
They all do that Sir.
Actually I have never seen that before and wonder if it would happen on mine if I tried it? Welded braces could stiffen up the box section, but the inside of the U section might need metal welded on to stop that happening. I did wonder if rust has weakened your part but it only looks like surface corrosion. I would expect the hefty rear Anti Roll Bar to stop that flexing, but I do wonder if that is normal?
Eric
