I recently pulled my '93 S&S accross the state of Michigan and down through southern Kentucky. I've also done the same with a 1500 Suburban, both 4WD. These Chevy trucks are the best. I didn't even know the trailer was back there, not only from a reserve acceleration standpoint and a vehicle dynamics stability point, but from a transmission busyness standpoint...the busyness algorithm is awesome. It only learns once you are towing a trailer - even on the highest grades.