what gears do i have

[dually kid]

i have a 2008 ford f350 dually and i get around 10-11 miles to the gallon. a friend asked me what is the gear ratio that i have and i couldnt tell him. how can i go about finding out what gears i have, is there a specific letter/number in the V.I.N. and if you have any suggestions on better fuel economy

[SuperCrutyPS]

Is there a tag on the differentials that say? Being that it's a dually, it may have 4.10s.

[dually kid]

not near my truck now id have to check

[dually kid]

any suggestions on fuel economy

[O2ShootTheJ]

you need to check the axle code on the door sticker then look it up

[dually kid]

thaks alot. one quic question though, should i call the dealer with the axle code or is there some where on the internet i could research this axle code

[SuperCrutyPS]

Just did a search for "Ford Axle Codes" and a bunch of hits came back so you should be able to find something out there.

[Gas Sucks]

What RPM do you run at 70, if you run in the 1700's your a 3:55, if you run in the 1800's you 3:73, if your around 2000 + your a 4:10. Im not sure if they had 3:55 for 2008, so its either a 3:73 or 4:10


My 08 had 3:73 and ran in the 1800's
My 10' has 3:55 and runs in the 1700's

[dually kid]

i run around 2000rpm at 70mph so according to this i have 4:10 which would explain my poor gas milage. anybody out there in the same boat. yall have been very helpful so far. i pull a fith wheel camper on ocasions and when i hook up to that thing u looking at aroun 8 mile to the gallon. i know a tuner would help but whats cheeper, new gears or a tuner

[badbrad777]

Originally Posted by dually kid

i run around 2000rpm at 70mph so according to this i have 4:10 which would explain my poor gas milage. anybody out there in the same boat. yall have been very helpful so far. i pull a fith wheel camper on ocasions and when i hook up to that thing u looking at aroun 8 mile to the gallon. i know a tuner would help but whats cheeper, new gears or a tuner

I have 37" Toyos on my truck with 3.73 stock gearing...effectively makes my gear ratio 3.35. I'm currently looking at going to 4.30-4.56s which will make my effective ratio 3.86-4.09. I currently pull a toyhauler, loaded about 12-13,000. While I can climb over most passes at about 70mph, I can feel a lot of drag on the truck...certainly a lot of stress on the tranny and the turbos are really sensitive to any climb in elevation. While I currently get about 9mpg towing, I think I might get better fuel mileage with new gears and lower EGRs.

A numerically low gear ratio can be just as bad as one that is too high.