We have an '01 3500 dually 4 X 4.......great clearance and no porblem with our new Big Country. The 5er we just traded in, not a Heartland, needed to have the axle mounts flipped in order to give us the needed clearance. This set up was a real pain when setting up......lots of blocks....high first step etc. Make sure you have at least 4 - 5 inches of clearance at the highest point. When we were shopping for our new 5er, I back the truck up to various brands to check for clearance.....much better than just trying to measure! Just my opions.