i have a '73 C20, 400 small block edlbrock 600CFM carb and intake, 350 trans,4.11 rear. it gets 11 pulling a empty 18 foot flatbed and about 8 carrying 13,000LBS of wood with that trailer. it probably would have got better if there weren't so many hills. but that engine only has 3-4000 miles on it.
