You can't expect a power wagon to get the same milage with the 273 as the barracuda. Your talking 1500lbs difference at least. Not to mentiuon the rear end ratio. The 360 will get better milage than the 273 will in that truck by a good bit. By the time you build the 273 to get anywhere near enough power to move that truck you've blown the gas milage all to crap.