Hitch classes explained
Hitch classes group receivers by rating: Class I up to 2,000 lb gross trailer weight with a 1.25 in opening, Class II up to 3,500 lb, Class III up to 8,000 lb with a 2 in opening, Class IV up to 10,000 lb, Class V above that with 2 or 2.5 in openings. The lowest rating in the chain (truck, hitch, ball mount, ball) is the limit.
What decides fit
The hitch maker lists the vehicles each hitch bolts to by generation. The same truck can take a Class III and a Class V; the difference is rating, receiver size and sometimes bumper work. Wiring is a separate part: most trucks need a 4-flat or 7-way connector, and many late-model trucks have a factory 7-way already.
Use it with
The hitch tables, where each row carries the maker's gross trailer and tongue weight ratings and the install notes.