With an original 6 cylinder your not going to see 12 mpg. The truck will probably have a 235 motor if its a Chevrolet.
gmc. prolly a 248, 270, 302. with the dump bed removed and replaced with an aluminum flatbed, overdrive trans and late model rear with radial tires, i'm hoping it will be more practical for everyday running around. the wheelbase is pretty short. if the truck is light enough, I think the original engine could pull it as long as I don't load it too heavy. I got 9 outta one with a 454. then..... there's always the 4 bt/ allisons idea.
