[tucsonjwt]

My 83 C20 with 454, granny 4 speed, gear vendor, and 4:10 rear axle gets 9 mpg city and 11 mpg highway. I used to get 11 mpg. city and 13 mpg highway before I replaced the original Qjet with a cheap online replacement.

You cannot expect the same mileage that a 1/2 ton will get because you are carrying and extra 1000 lbs. of vehicle weight.

Everyone I know who has a 3/4 ton old truck is getting about 9-10 mpg in town with a gas engine. Diesel engines get about 17 mpg overall.

To quickly check your odometer accuracy: drive on the expressway and note the odometer reading when you pass a mile post, then note the odometer reading when you pass the next mile post. See how close your odometer reading is to one mile.

Idling in town at stop lights is what kills mpg on the heavy trucks.