Ive heard of class I, II, III, and IV for towing travel trailers, and the class V is normally a 5th wheel or gooseneck type hitch. I Tow a 31' without any kind of weight distribution system on a class IV with my F-250. On the other hand we have to use weight distribution with the F-150 and a 29' so the tow vehicle makes a big difference. I have looked at the husky system and I like the way it hooks up and works.
I think that there may be a class V receiver, if so its probally 2 1/2" and the standard receiver are 2".
1976 Soveriegn 31'
F250 Turbo 7.3L Diesel
WBCCI # 3516