I like the 6.8 and 5.4 for a gas motor in a truck. A local excavation company has an extended wheelbase F350 with a giant utility box and is always dragging a T300 Bobcat eveywhere and has been doing so since 1999--with a 5.4. It sounds like a sewing machine going by. I don't have any experience with either motor, but they way they are set up, they are built for truck service. A long stroke and small valves. I don't think either gives up much to a diesel in such a truck. It's a cheap engine, too.