Can't find any Itasca hitch brand- is that the brand name of the RV the hitch is on?
If so, 500 pounds might be the vertical hitch weight limit of the rig itself, possibly stamped on the hitch at the request of the RV manufacturer. This seems likely to me since looking at the Itasca page just now, I don't see anything with over 5,000 pounds of tow capacity.
Link.
Do bear in mind that he "10,000 lb. tow limit" you see on the hitch is irrelevant if the rigmaker says the limit is lower. You could probably bolt that puppy to a VW Beetle, but that wouldn't mean it could pull 10,000 pounds!
