I have an 06 FX4 screw..just bought it last month. It has 5.4 and fact 20 wheels. How can I find out what the gearing is in it. 3:55 or 3:75? ANy help...is there a code lable on the truck to look for?

 

There is a code on the drivers door.

 

http://www.ford-trucks.com/article/i...r_Decoder.html

 

Get the code off the door and it should be on this list.

The following lists the gear ratios on rear axles.
19 — 3.55 non-limited slip (Econoline, F-150)
18 — 3.08 non-limited slip (F-150)
17 — 3.31 non-limited slip (Econoline)
H9 — 3.55 limited slip (F-150, F-250)
B6 — 3.73 limited slip (F-150, F-250)
24 — 3.73 (Econoline)
32 — 4.10 (Econoline)
35 — 4.09 (Econoline)
34 — 3.73 (Econoline)
39 — 3.55 (Econoline)
52 — 4.10 (Econoline)
56 — 4.10 (Econoline)
81 — 4.63 (Econoline)
27 — 3.31 non-limited slip (F-250)
26 — 3.73 non-limited slip (F-250)
41 — 3.27 non-limited slip (Explorer/Mountaineer)
45 — 3.55 non-limited slip (Explorer/Mountaineer)
46 — 3.73 non-limited slip (Explorer/Mountaineer)
42 — 4.10 non-limited slip (Explorer/Mountaineer)
D1 — 3.27 limited slip (Explorer/Mountaineer)
D4 — 3.73 limited slip (Explorer/Mountaineer)
D2 — 4.10 limited slip (Explorer/Mountaineer)
84 — 3.45 non-limited slip (Ranger)
86 — 3.73 non-limited slip (Ranger)
87 — 4.10 non-limited slip (Ranger)
89 — 4.56 non-limited slip (Ranger)
F6 — 3.73 limited slip (Ranger)
F7 — 4.10 limited slip (Ranger)
92 — 3.08 non-limited slip (Ranger)
R5 — 3.55 limited slip (Ranger)
91 — 3.27 non-limited slip (Ranger)
96 — 3.73 non-limited slip (Ranger)
R6 — 3.73 limited slip (Ranger)"

 

That's a nice link to save! I have been doing a search everytime someone asks about the gears.

 

Your axle code on that truck should be B6, 3.73 w/ limited slip.

 

Yep..thats it. Having 3.73 just helps me think more of going 35 over 33s. Thanks for the info.

 

That's specifically why I bought an FX4.
I still plan to re-gear one day but I'll be able to deal with 3.73's and 35's since I don't have anything to tow right now

 

or you could look at the axle tag on the diff cover

 

I have an 06 screw with factory 20's. According to that chart I have 3.73's. I'm not sure though, I bought it used. This truck cruises at a few hundered RPM's lower than my 05 which had 3.73's that I bought new. It had 17's though.

Seems most screw's I looked at had the 3.55 gears.

 

Most of the XLT models that I looked at had 3.55's too.
I bet the tires on the 20's have a slightly larger diameters than your 17's did.
I have to say that the 3.73's and stock tires feels nice on the highway, my last truck (sport trac) had 4.88 gears with 33" tires. Great off road but it was pretty annoying at 70+ mph!

 

CHECK YOUR AXLE TAG!!!!

 

That means I'd have to bend over. Not happening.

 

Sweet! I was wondering what I had. Thanks!

 

On my 04 Screw....the door tag says 19, so I figured 3.55's. But my speedo was off, still have the 255/70R17 stock sized tires....so with my 1745 Max tuner I switched it to 3.73's and the speedo is dead on......go figure.