Had a long, wide bed '60 C-10 with 6-cylinder, three-speed that would get 16 with a bit of luck. Swapped it for a new '65 C-10 with short Fleetside bed, 283 V-8, 4.11 differential, and a 3-speed manual overdrive that worked when it wanted to (once in a while) and managed 12-13 mpg. Thought it was awful for a small pickup running empty.
