I just got done towing my toy hauler to Vegas and let me tell you that it was not fun towing up the big grades. My toy hauler is 5500 pounds dry and thats how I was towing it. The trans was getting hot and the rpm's were at 4500 to keep up at 55 to 65 mph. Flat straights were not a problem but I now wish I would have got the 2500. Anyone have any solutions??? Truck 2007 Silverado 4x4 5.3, 3.73 Rear end.