For your future reference: I've had nothing but good experiences towing heavy bulky trailers with my '97 Expy 5.4l 4x4 equipped with four corner air, 3.73 axle, factory HD tow package, bilstein shocks on rear, optional 17" wheels and Bridgestone Dueler AT Revo tires inflated to 42 lbs on the rear, 38 lbs front. I tow a 26' x 8" TrailLite travel trailer (dual torsion axles) that tips the CAT scales at 5480 lbs. I towed 4500 miles over the top of the rockies from north to south, passing many other rigs on high passes over 10K ft, like Wolf Creek Pass. It was first gear, but the speed limit was maintained at all times, the Expy ate it up and never overheated at all. After staying in WA state for two weeks we then covered the high Sierras the same way as the Rockies only going North to south, then back to TX. Nary a problem, without a weight distributing hitch, using only two antisway bars by Reese. Tongue weight was balanced out with water and sewage on board at 6.8% of trailer weight.