What is the lowest gears I can get for my 99? I am pretty sure I have the 3.73 stock standard setup now!

 

How low do you want to go? I know I've seen 4.56 available for the 10.5" rear, and I think I've seen 4.88's and maybe even 5.14's.

Way too low to run down the highway with 31" tires.

 

ringpinion.com has has 3.54 thru 5.38,s for the 10.25 and 10.5. they have an add in the most recent Diesel Power magazine

 

OK.......I dont' do hardly any towing and was looking for increased gas mileage and just wanted to see my options........70mph with 2,000rpm's would be 3.73 right? What would be the best for me?

 

Oh, you want higher (numerically lower) gears. Something like a 3.55 or 3.27 gear. The lower gears (higher numbers) will kill your milage on the freeway.

 

yes but with a high gearing setup (low number) you wont want to haul anything much, because it is much more stressful on the drivetrain components than a 4.10 would be. it would be nice when you are crusing, you could be at 75 mph at the same engine RPM when with the old gears you were at 65

 

I have a '94 F350 Dually w/ 190,000 miles. My milage is only 10-12 mpg. With saddle tanks and $2.85/gal., it is an expensive truck to drive. About $70 to fill up now. I am interested to find out if my ol' truck can handle a rear end ratio change this late in her life. It would help out my "back pocket." I have 4:10's and want to go to 3:73's.

 

Welcome to FTE dinka0702 Please take a moment to read our forum guidelines.

4.10 to 3.73 is a pretty small difference...probably wouldn't ever offset the cost of the gears in fuel savings.

 

That was my fault......I typed that wrong!!!

 

I know of a 2x4 that has 3.08's claim he gets 28 MPG, but has to really ease into the throttle. I actually lost milage with my 3:55's, but I drive it hard, so it took more to get going, I gained milage on the open road, but made up for it in more used to get rolling.

Diesel Rod