Noticed another clarification that's needed...

...the 750 tongue weight and 5 K lb tow weight limits for a Class III hitch are ALSO related to the wheelbase of the truck, and control issues...such as being able to maintain control while driving through a cross wind, high crowns, over bumps, etc...and not the structural strength alone.



IE: The hitch itself is not always the weak link in the chain, and the Class weight limits can be imposed to account for other factors.