1969 f100 p/u

[rsparks100]

what rear end ratio could i use in this 9in rear end to get better fuel mileage

[heep70]

Doesn't this belong in the drivetrain forum. Moved.

[CbiScuT]

First off, I'd want to know what kind of tranny you have, before I would suggest an different ring and pinion. So...

[gmcjimmy88]

What is the drivetrain currently in your truck? What ratio do you have? How much are you willing to sacrifice to0 get better gas mileage. In other words going from a 4:10 to a 3:07 could get you better gas mileage but you might lose some take off power. Also do you drive in town or on the highway mostly? A higher gearset (smaller number) could get you better mileage on the highway. For instance my 05 GMC 2500HD with 4:10 Averages 9-12 MPG. That same truck with 3:73 I have been told gets 12-16 MPG but can't get 10,500 pounds moving from a stop. The main questions are what is your current set-up and how do you use it mostly.

[69bluef100]

with a mildly modified 300, T-18, 3.50's and 235/75/15s (30" or so) I get 20mpg with my 2wd F100. Doesn't seem to change on the highway or in town.