IMHO, a diesel is cheaper in the long run, I have a heavy enclosed trailer, and pulled it for a long while, with a Ford Van, did it OK, just not much power/torque, and the milage was 7-8 mpg, I also towed the same trailer, with an F-150, pulled it ok, mileage was not quite so bad, but the pucker factor was real high, it had a 3:70 rear gear, but it scared me bad a couple of times, so I started looking for Diesels, and ended up with an Ebay bought, 1997 F-350, with the 7.3 IH diesel, crewcab, all power, automatic and air, 2 whl drive, posi and a dually, and have not been sorry, mileage runs steady at 14-16, no pucker factor at all, engine is just short of 400k, and runs super, and the trailer doesn't intimidate the truck at all, I personally wouldn't recommend the 6.0, but the 7.3 was still available thru 2003, and that ought to get you a nice truck, the 1997 was actually in production almost 3 years, but still as a 97, I think early 1999.5 was the first official body style change. Good luck! Bob!