ok heres the deal, i am getting a new road rig. plan on a mini motor home/hippie van set up. i burn down the road between colorado and here and i don't want to stop. i don't want to spend more than 7k on it. i will finish out the inside like i want and i plan to but a big tank from a cut away van to hold a butt load of fuel. i need this to get the best miliage i can. i am converting it to a 4x4, yea i know it wont help miliage, but i need it in the winter. and they want to much for the quigly conversions. so what should i get a 6.0 or a 7.3 i have found more than a few in my price range. and what chips for miliage? i plane to open up the exhaust and free up the intake to help. and i figure a set of 235/85/16s at 80 or so psi will help. any ideas?????????????