Ford made the good ol' 240 and 300 inline sixes starting in 1964, and they had the torque and longevity to be great truck engines. By 1983, however, pushrod sixes were going the way of the vinyl LP- quick, get a metric designation on that thing, so buyers will think it's one of those newfangled V6s! We're a little skeptical that a Late Malaise F series pickup ever got 30 MPG highway, but maybe that test was done at a "highway speed" of 42 MPH, using a liquid measurement known as "Ford Truck Gallons," which are equal to 1.5 regular gallons.
Had one of those once, got it to save fuel. Called it the Brown Bomb. 85 model, CA spec, had a funky retrofitted carb on it forget what they called it but to me it was satan's heart. Think of it this way, you have a carb, it still has fuel bowls, needle valves and mixture screws, but it also has a fuel injector on it. Yea, exactly. So yea bought it to save fuel, spent much more on repairing the junkheap. Lets see in 6 months, the head was replaced, the AC burst into flames, the tranny died, the smog pump went out, satan's heart went out, the exhaust manafold cracked and the chopped in radio never really worked. When it ran it never peaked above 16 MPG and when the trip ODO broke it was always a crapshoot if you were going to run out of fuel. Oh yea forgot to mention the fuel gauge didn't work either.
After all the hard plastic vacum lines busted I tried for weeks to replace all of them just to keep this thing running. I failed. Ended up selling it for $200 bucks.