Where can I find the effects of operating an overweight vehicle?

I have worked on every manufacturer of trucks for truck bodies and equipment and and talked to end users since 1978. I have also sold nothing except trucks for the last four years and you are corect. An overloaded truck will bring premature and costly repairs. The wear items for overloading a truck starts with excessive brake wear, over worked transmissions and rear ends (from starting and stopping) and suspension wear and tear. Shocks will not last as long as normal and occasionnaly springs will flatten. If over loaded too much frames have bent or cracked. As a rule the people that buy and overload these trucks will blame the manufacturer for building a piece of crap. Almost all manufacturers build very reliable equipment when used for the guide lines provided to each GVWR. Remember that payload is not the GVWR of the truck but the weight of the truck, full of fuel and driver. That weight is subtracted from the GVWR to provide your payload. Even then it is to be distributed evenly through out the bed. Hope this helps you with your boss.