And the increased GVWR. With the 3500 SRW you can just about haul an self-contained camper if you are very careful with the model you get and the supplies and people you add. With the 3500 DRW you can haul the big ones. With the 2500, it gets difficult to find a camper that has full features, some extra load capacity for "stuff" and people, and still be within the GVWR. If all you want to do is tow, the 2500 does it. If you need to haul a bed load, or you want that option for the future, the 3500 will keep that legal.