Just remember that the only difference between a 2500 and 3500 might be the springs. The Axle rating and tires might be the same between the two. If so then airbags will help any excess sag but won't change the payload specification on the door decal. But will give you an equivalent load carrying capacity as the 3500. Pulled a 2006 Keystone/Montana 3400RL 38' 5th wheel 13,957 GVWR for 9 years and over 35,000 miles on the RV/Truck combination with a 2003 Ford f250 7.3L 4 x 4 without problems. Sold the RV, truck still going strong with 185,000 miles on it. I don't recommend it but sometimes we get all caught up in numbers.