The standard rearend ratio in those 6-cylinder Chevy pickups was a 4.11 and they were not noted for gas mileage. Most of them had trouble getting 15 mpg. My '60 with a 235 would touch on 16. My '65 with a 283 V-8, 4.11 rear, and overdrive that worked when it wanted too, which wasn't often, couldn't get 15 with the O.D. working. Most of the time it got 12-13 mpg. That would be a big OUCH with today's gas prices. Swapped it for a new '69 Ford with a 360 V-8 and about a 3.50 rear that got 15-17 and had a lot more power. I though I came out way ahead on that trade.
