I have a 2006 F150 Supercrew looking to upgrade the ring and pinion to a 4.88 or 4.56 to help with the bigger tires. What is the stock on a FX4 is it the 4.10? And will going to a 4.56 or 4.88 be noticeable.

 

There should be a tag on your door with various codes on it. One is the Axle code. It will be 2 digits such as 2 numbers or a letter and a number. Get that, and then in the Articles and How To section, there is a thread on decoding the VIN and tags. Look in there for your code.

 

Just a note, I assume you realize you have to change gears in both axles, or you cannot use 4x4.

 

Also highly unlikely you have a 4.10, unless you have the 8200lb payload package. More likely a 3.73.

 

Did look at the tag on the door looks like it is the 3.73 will I see any benefit if I upgrade the Axles to a lower gear. Either 4.10 or 4.56. I was thinking the superior gears for the upgrade http://www.superioraxle.com. Front and rear I just don't know if this is completed that I will get what I want. What I really want is the throttle response that I don't seem to have. I have a K&N Cold Air Intake and a Saleen exhaust system and using the Evaluation Edge. I know that I will never get the quickness of a carburetor engine but thought that with the high torque in the lower gears I would gain a little. Let me know completely wrong on this or just over thinking things.

 

3.73 to 4.56 would make a big difference. What size tires are you running?

 

305 55 20. Just under 34"

 

Power train is still under warranty should I even mess around.

 

I could not find that thread. I even looked in the old articles link...I probably missed it. My truck's axle code states B6 and I seen somewhere that that is a 3.73 gear...correct?
I just bought this truck and it is an 05 FX4 Screw, 5.4 with 275/70R18 tires. I'm not sure about the rest of you Screw guys, but my truck's MPG sucks...literally, or is 12MPG normal for a Screw? I wouldn't think that size tire would drag te truck down that much.

CDB03STX

 

B6 is a 3.73 limited slip.

 

Sorry to hijack your thread but I have been looking all around and can not find the the de-coding post. My sticker says H9 under axle. What gears are these?

 

That is a 3.55 limited slip.

 

alright thanks kingfish, if you dont mind do you think you could make a list of the code and what gears they are and post it here or PM me.

 

https://www.f150online.com/forums/ar...e-sticker.html

 

Thanks glc, i dont know how i missed that when i looked.