I had a 76 short-bed F-150, 300 Six and three on the tree, 30k miles when I bought it. Could start from a dead stop in third gear without feathering the clutch and it got a solid 13 MPG - highway, city, loaded, empty, taking it easy or running the hell out of it - 13 MPG, period. I kept a note pad in the glove box for as long as I owned it and recorded the miles and gallons at every fill-up.Wouldn’t worth a darn on gas mileage though was it? Well let me say this. It might not have mattered much because it probably got 9 loaded as well as empty! Everyone I know that had them they got 9-10 miles to the gallon.
I always thought that 13 MPG was awful mileage, but 9 - 10? Holy cow!
The gas wasn't what hurt me. Every time I drove it I had to replace something on it. I traded it toward a brand-new 85 Nissan short-bed and every time someone asked me why I bought the Nissan, since I already had a Ford, I told them I needed something to run back and forth to the parts store with to keep that Ford running. Mostly anything electrical.
The 300 was an amazing engine, but the 2.4L NapZ in the Nissan was a bit of a little monster itself. It would SCOOT.