I want to change the gearing out on my truck from 4.10 to 3.73, in hopes of gaining some MPG, would this work and would a 2007 axle fit under my 1999? both trucks are F250's the axle from the 2007 would be from a diesel, not sure if this would make a difference, thanks for any help

 

df,

I'm not sure if the '07 is interchangable with your '99, but I can tell you that the mileage gain from 4:10 to 3:73 would be ever so slight. Too me it would not be worth the effort for the minimal mileage gain alone. If they are interchangable and you were in need of replacement gears then of course it would be worth it.
4:58 to 3:73 would make more of a substantial difference as would the even lesser 4:30 to 3:73, but 4:10 to 3:73 really is not much of a jump.
But of course if you got your mind set on it,,, let'r rip!

Edit:
I did a quick search and it does look like the '07 is interchangable with your '99.

Rick...

 

Thanks, I'm not towing anything big just a small motorcycle trailer and i mostly run from home to school and back, which is just over about 2 miles, i figured that the gear change would make it accelerate easier and not make the motor work as hard, and thanks for the check on whether it would fit or not,

where did you search to see if they would fit? just curious

 

i have a 99 with the 4.10 and it out accelerates my friends 01 with 3.73's. we have pretty much the same exact setup other than that. just my 2 pennies!

 

df,

I just checked out a couple of random parts (axle) suppliers.

Bronco Graveyard 1
Bronco Graveyard 2
Bronco Graveyard 3


Rick...

 

Have you considered a SCT X3 tuner with custom tunes? You will have three custom tunes available to you, one of which can be an "87 Octane - Economy" tune.

Contact Mike at 5 Star Tuning... he can provide more information.

5 Star Tuning
1209 Hill Harrell Rd.
Effingham, SC 29541
(843) 667-3595

Got a 5.4L V8 Ford F150-F250-F350-E Series Van?

 

it would make your engine and trans work harder going that direction in gearing. like getting taller tires...same effect kinda. I would leave it unless you need your gears replaced.