Originally Posted by MonkeyBiz
My experience is hit and miss with the 6.5s. A friends of mine had a Blazer with a 6.5 (from the factory) and it towed a jeep on a trailer and barely knew it was there. He then got a 1/2 ton Chevy, (again, had a 6.5 from the factory) and it struggled to hold 60 on the highway with the exact same jeep/trailer combo, and was in general gutless.
unless there was something wrong with the engine, I would bet the 2 had different gearing, and or tire sizes.