Hello,
I am looking to swap my rear gears from 3.55 to 4.10, I am posting some pix of the tags on the rear end. Really don't know if 4.10 is best or 4.56. Please give advise. What I am getting for the tags are:
1-3.55
2-12 bolt
3-H9 Axle

 

That's a 9.75" rear. Why do you want to change gears, and what will you be doing with the truck? Any mods such as larger tires or a lift?

You will need a programmer with (preferably) custom tunes when you get done.

 

I would like a lower gear so to come off the line better. This truck in 2003 5.4L was sent off to L.A. West to have the conversion kit put on, With that conversion come 20 inch wheels and tires. Same as the Boss truck in 03.
Yes, I will be getting a custom tune and programmer. It is all factory at this point. Only a limited number of these trucks was sent off. I posted pix in the gallery of it.
Thanks,
Mac

 

If you aren't going to be towing, 4.10's should be fine. 4.56's would be a bit busy on the highway.

 

What size tires are on those 20" rims, diameter of the tires?

 

275/50/r20

 

Well, they are actually a little smaller in diameter than stock 265/70x17 tires. Stock on my truck anyways.

 

Is yours 4WD or 2WD?

 

9.75 and Limited slip 3.55

I'd look at 4.10s and keep your current carrier

 

4WD The FX4 in my signature. I see now your plaque that says yours came with 255/70x16s which are a little smaller in diameter than the 20s on it now.

 

Yes stock, After Ford sent it to L.A. West. The truck was converted to 20's.

 

3.55 to 4.10 done. I love it.

 

I'm sure you do! I would like to have 4.10s in mine but not enough to spend the money to get it done for the front and rear.

 

Mine wasn't to bad, Its 2WD. Would really like to get a tune now.

 

I bought a new 2000 Scab 4x4 with the 5.4 and put 105k miles on it before selling it when gas prices were over $4/gallon. In 2009, I bought my current 2002 Scab 4x4 with the 5.4 that had 69k miles on it. The 2000 was noticeably more powerful than the 02 until I installed a Superchips program that really helped. I estimate it added 20hp. I suspect the factory tune of the 2002 was less aggressive than the 2000 due to trying to meet tighter emissions standards. I don't know for sure but afterwards the 02 runs great for what it is and the gas mileage is improved. I think you will like a tune.