Those of you that have out 4.10s in your truck how much improvement has it made?
What did it cost? (parts and labor)
How much MPG loss?
For the $$$$ did you think it was worth it and would you do it again?
Any pitfalls?

 

The pitfall is high rpm on the highway unless you have very large diameter tires. You might do better with a taller differential gear and run with OD off while pulling your trailer. I assume you are talking about trailering and not racing your truck.

I am running a 3.27 differential gear and with OD off I can pull my 4000 trailer very well. In fact on level ground I can pull it in OD. I have a 4.6 F-150

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97 4.6 F150, 1/8 = 10.885 @ 64.10 mph, 88 5.0 Mustang 1/8 = 7.191 @ 94.76 mph

 

4.10s are the best. I would do it again in a second. This in my opinion is the way the truck should come from the factory.I noticed a difference of about 250-300 rpm at highway speed.I added a Superchip when I did the gear swap so gas mileage has remained about the same.
Thus far the only pitfall has been getting the speedometer recalibrated. Superchips has found a problem with the speedometer program and are fixing it now.Other than that I have not had any problems.

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99 F 150 4x4.ORP,S/B 4.6 4.10 gears, Gibson 3" cat back. K&N filter. Superchip