The 2006 1500 Silverado I had last was in the series that had rust problems with the receiver hitches, so I replaced that one with a class V hitch.
When I traded it for a 2013 1500 Silverado, with "tow package" in April, I never though about there being a problem. Last week a friend of mine with an 07 Silverado told me he had recently sold his goose neck camper (that he pulls with a Ford Super Duty) for a bumper hitch model. In the process, he found out his Siverado only had a 5,000 lb receiver hitch, so I came home & checked mine. Sure enough, even though the pickup is rated as 9,500 lb. towing capacity, only a 5,000 lb hitch! Before that day was over, I had a new class IV Curt hitch ordered from Summit Racing @ $147/free shipping. It came yesterday by way of UPS, I said something to the driver about it & he told me he had the same problem with a Ford "Super Duty"!
Started at 7:30 this morning, dropped the spare, took the factory hitch off (took longer than mounting the new one). Haven't weighed the factory hitch, but there's no comparison between the two! Working by myself & including a couple breaks, it took me 1-1/2 hours with hand tools to install.