1984 Chevy regular cab flatbed dually, 454 with 2 1/2" dual exhaust and 12" chamber glasspacks(nice and LOUD
), stock air breather and Qjet, SM465, 4.10 gears, 235/85/16 rubber at 60psi. Right now I get about 6-7 in town and highway is close to 14, that's doin' around 50-55. Any higher and the gas gauge moves to the left real quick.