Just a thought
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Just a thought
I have a 2001 F150 off rd pkg. I love this truck. My only issue with this truck is the 3.55 differential. I want to eventually change it to at least a 3.73. I have changed out 3rd members on older Fords before which was pretty easy. But the newer stuff I know I have alot to learn and that can be dangerous. How hard will it be for me to change it. It only has about 83K on it now. I probably would not change it for awhile I was just curious how much of a project it will be.
I get about 17 to 18mpg now, any thoughts how much worse my muileage would be with the gear change.
Rear diff not front. I have no desire to mess with the front diff.
I get about 17 to 18mpg now, any thoughts how much worse my muileage would be with the gear change.
Rear diff not front. I have no desire to mess with the front diff.
Posting Guru
Joined: Oct 2005
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From: Louisville, Kentucky
You will have to change both differential gear sets, can't change just the rear unless you never plan to use 4x4 again. Mileage won't change much, might even get a little better especially if you go to bigger tires. Good luck! 
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Joined: Sep 2002
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From: None of your business
IMO I'd skip right past 3.73 and go for 4.10s. 3.73s only offer .18 more gearing. You'll lose 1 or 2 MPG on the highway at 70+ but at around 65 you'll probably still get 17-18 and in the city you might gain 1.
Mike
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I knew I had to change both what was I thinking. Brain fart I guess. 
I'm runnin the stock 265/70/17 on it now, Where I live and go hunting it is pretty rocky and I like skinny tires in the rocks. I could not image going bigger or any wider than I have. I would love to keep the same height and go skinnier with the width. Since I just spent $800 on tires last year that will be awhile.
It actually does pretty good with the 3.55 and I would consider 4.10 and that maybe a better option. I definetly would not go higher than that though. I drive it more on the asphalt than off road.
I'm runnin the stock 265/70/17 on it now, Where I live and go hunting it is pretty rocky and I like skinny tires in the rocks. I could not image going bigger or any wider than I have. I would love to keep the same height and go skinnier with the width. Since I just spent $800 on tires last year that will be awhile.It actually does pretty good with the 3.55 and I would consider 4.10 and that maybe a better option. I definetly would not go higher than that though. I drive it more on the asphalt than off road.
