Thanks Jack, yep, that's it.

 

Ok well either I had changed mine and didn't remember or mine didn't default to 3.73, I was all excited thinking I was about to improve my current performance but low and behold....set on the proper 3.55

 

Do most 04+ F150's use the 3.55 gears? I don't know what the door codes mean. I have a '05 F150 with the 5.4l. Not trying to hijack the thread.

 

Oh, no harm in hijacking, we do it all the time. If you do a Google search, you'll find several sites that give you a VIN decoder. I'm too lazy to look for one right now.

But, I'm not sure the gear ratio is in the VIN. There is a tag though, on the differential that is supposed to give that information to you. I've seen the tag on my truck but I've never crawled up under there to read it.

- Jack

 

Thanks Jack. I will check that out.

 

Here you go. That must have been Janet, not Jack.

Yeah check the driver's door Jamb and get the code off the sticker.

19 — 3.55 non-limited slip — F-150
25 — 4.10 non-limited slip — F-150
26 — 3.73 non-limited slip — F-150/Mark LT
27 — 3.31 non-limited slip — F-150
B5 — 4.10 limited slip — F-150
B6 — 3.73 limited slip — F-150/Mark LT
H9 — 3.55 limited slip — F-150
18 = 3.08 non-limited slip — F-150

 

Well duh! Right there under the word "Axle"! I gotta tell you, it's hard to beat a jaybird at this game. At least though, it wasn't in the VIN, so Janet was half right.

So, I crawled under my truck and looked at the tags on my differential. One tells me to use a synthetic fluid (so it's not much help). The other has several numbers in groups of one or two digits. The one group that looked promising was: "L73" on the second row (above it was a "3" by itself) - so, if this refers to 3.73LS (which is what I have), the "tag approach" is a bit cryptic too.

I always find myself wondering why manufacturers find it necessary to use "codes" for useful information.

(And now someone is going to probably tell me what all the numbers on the differential tag mean, just to humble me even more. I keep trying to build up my "attaboys", and all I really seem to accumulate is "aw sh*ts".)

- Jack

 

You are pretty much right on with the tag. Just ignore the upper line as it only helps the dealer. The lower line should always read something like 3 (sometimes this is missing because of the hole punch) L 73 88. That would be an 8.8" with 3.73s and a limited slip. Other rear axle found in the F150 include the 9.75" (example 3L73 975) and in rare cases the 10.25" (Example 4L10 1025). The 10.25" were the seven lug F250 LD sold in the US and as the F150HD sold in Canada).

 

guys not to but in on your conversation tion but i have a edge programmer on my 2004 f-150 i keep seeing send it to bill he can make do ths and that to enhance even more performance if this is true how do i get ahold of this gentleman thanks

 

no butt in at all!

www.powerhungryperformance.com

 

You will see posts by him on here occasionally. He is ASEMechanic and his wife is GroovyChick. Bill and Corey.

 

They are VERY busy people, but their customer service and genuine care is 2nd to none! That's rare in today's world!

 

Thanks for the gear information, Bluejay and Jack.