Peak horsepower tells nothing useful about how a vehicle will perform as a platform for towing, what is more important is torque, and especially low rpm torque.
The old 12 valve cummins 5.9 liter diesel made ~220 hp, well down on the frontier's 260 hp. But, that engine made 440 ft/lb of torque and made that torque across the rpm range. I can guarantee a vehicle with that engine would handily out tow the 260 hp V6.
