I recently acquired a 1985 f350 2wd dually 4 speed flatbed with 3.55 gears. The truck runs great starts instantly, Although it has trouble maintaining speed on hills without having to grab third and wind the **** out of it. Things I have done are, Remove the restricter from the air cleaner, Bump the timing a hair, and uncork the exhaust. All of which helped some but not much. It has fairly new filters and doesn't smoke abnormally, Just a slight black haze when pulling hills. This is my first idi so this may be normal as far as I know, Just seems though it shouldn't struggle so much. Kinda makes me wish ida kept my gasser.