All class As I know if have a 10k hitch. I have seen class Cs try to tow inclosed with a 5k hitch and bent the rear of the coach. The structure from the tires back is not designed to handle the load and will flex and eventually fail. You can't just add a 10k hitch to replace the 5k, you must add structure, generally 2 x 3" tubing from in front of the wheels to the hitch with X bracing. Good luck getting someone to do it for you.