My dad is looking for a used 2500 and found a clean 2006 with the 8.1 V8. Most of the trucks he has seen have the 6.0. He is concerned the 8.1 will really suck the gas more than the 6.0. Can someone give me some idea of the diff in fuel consumption between the two? This isn't a daily driver, but will be used for some towing and general truck stuff.