That was only a guesstimate ... and Im usually Wrong on swags.
Its the 322R so about 2200 pin. I got with a long haul trucker and the guy who sold me the truck(local dealer rep), both in my RV club. They said I should have no problem with the 322R. I weighed the truck with wife and fuel and it came out to 6400# total. Near as I estimate I have about 3200# available on the rear axles (max rear - actual). The guy that owned the truck ordered the HD with the Heavy duty Rotors and the Overload spring pack.