I have the same problem on my truck ('49 chevy), and i am just hoping the bed covers enough of it! but actually i will be adding reinforcement inside as well because i want to remove the original center cab mount (allows for movement) and make a cab mount on each side. Not sure on how your cab mounts but may want to do the same. Will be tricky i know because it will want to pull the metal in if the reinforcement is not darn near perfect, but at least then its solid and you can work on it without it moving around on you!