decode the diff tag
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Senior User
Joined: Oct 2012
Posts: 470
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From: Havillah, WA
decode the diff tag
Hi all, quick little question. I was curious as to the diff ratio. I figure it's the stock 3.73 but figured wouldn't hurt to know for sure.
No code on the door sticker (no shock there)
Pulled this tag off the rear diff (i didn't see one on the front diff)
Didn't match any of the numbers on the tech folder article so didn't know what i was looking at. Figure one of you ford gurus can decode it without blinking an eye.
Thanks for any help.
No code on the door sticker (no shock there)
Pulled this tag off the rear diff (i didn't see one on the front diff)
Didn't match any of the numbers on the tech folder article so didn't know what i was looking at. Figure one of you ford gurus can decode it without blinking an eye.
Thanks for any help.
Thread Starter
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Senior User
Joined: Oct 2012
Posts: 470
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From: Havillah, WA
Well did some internet searching and found this link to a list. I don't know if that's accurate or not as every page i find with decoding seems to have different opinions on how it's supposed to look but this list did have a decoder that actually matched the numbers on the tag (well at least the top numbers) So looks like the 415B on the top row means a 4.30 Limited Slip? that sound right to you guys?
Ford Rear Axle Assembly Identification - Page 13 - FORDification.com
Ford Rear Axle Assembly Identification - Page 13 - FORDification.com
Senior User
Joined: Nov 2010
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Well did some internet searching and found this link to a list. I don't know if that's accurate or not as every page i find with decoding seems to have different opinions on how it's supposed to look but this list did have a decoder that actually matched the numbers on the tag (well at least the top numbers) So looks like the 415B on the top row means a 4.30 Limited Slip? that sound right to you guys?
Ford Rear Axle Assembly Identification - Page 13 - FORDification.com
Ford Rear Axle Assembly Identification - Page 13 - FORDification.com
Mountain Pass
Joined: Jun 2012
Posts: 193
Likes: 34
From: Upstate, SC
Clean the area around the bolt. You might find a 37 under the dirt. Top left numbers on tag is gear ratio. If its a locker, it will have a L between first and second number. 3 73 s.... is open 373 ratio. 4 L 30 s... is limited slip 430 ratio.
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From: North Dakota
Here's a bit of info, here is two different ford tags, one is older, and the ratio is in the top line, other is newer(off my Ex) and it's the first in the bottom row.
First tag reads 3.54 gears the second 3.73s
First tag reads 3.54 gears the second 3.73s
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Mountain Pass
Joined: Jun 2012
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From: Upstate, SC
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Postmaster
Joined: Aug 2012
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From: Westfield, Indiana
That is a sterling 10.25 not a 10.50, not sure that it really matters at this point but it didn't come with your truck from Ford. All Excursions got 10.5 off the line - unless yours got some weird left over axles. 
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Joined: Oct 2012
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From: Havillah, WA
Someone was ble to discerned from my vin that this truck did come with a 4.30 w/ limited slip from factory but I do know it was in an accident a few owners back. Hit on the rear drivers side fender and salvaged. I was told it was mostly body damage that was repaired but Maybe they swapped out the axle? On the other hand do mechanics typically swap out the diff tag as well? The 415b code on the top most line seems to designate it as an X differential with the same 4.3 and limited slip that the vin pointed at. So everything seems to match up except this new 10.25 info. How can I tell the difference visually from one to the other. I'm gonna pop the cover today to do the diff fluid so I'll take a pic of the guts.
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Joined: Aug 2012
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From: Westfield, Indiana
Sammie, was this aimed at me? Are you saying the diff pic I posted isn't stock? What's the difference between a 10.25 and a 10.5? (Please don't say .25)
Someone was ble to discerned from my vin that this truck did come with a 4.30 w/ limited slip from factory but I do know it was in an accident a few owners back. Hit on the rear drivers side fender and salvaged. I was told it was mostly body damage that was repaired but Maybe they swapped out the axle? On the other hand do mechanics typically swap out the diff tag as well? The 415b code on the top most line seems to designate it as an X differential with the same 4.3 and limited slip that the vin pointed at. So everything seems to match up except this new 10.25 info. How can I tell the difference visually from one to the other. I'm gonna pop the cover today to do the diff fluid so I'll take a pic of the guts.
Someone was ble to discerned from my vin that this truck did come with a 4.30 w/ limited slip from factory but I do know it was in an accident a few owners back. Hit on the rear drivers side fender and salvaged. I was told it was mostly body damage that was repaired but Maybe they swapped out the axle? On the other hand do mechanics typically swap out the diff tag as well? The 415b code on the top most line seems to designate it as an X differential with the same 4.3 and limited slip that the vin pointed at. So everything seems to match up except this new 10.25 info. How can I tell the difference visually from one to the other. I'm gonna pop the cover today to do the diff fluid so I'll take a pic of the guts.
Yes that was directed at you. If it's a 10.25 the yoke is most likely different unless someone has changed it. The odd thing is that I don't show Ford ever made a S415B in 10.25 Ring Gear.
I looked it up as well and found the same thing that S415B was put in Excursions but I also can't find any mention that S415B is a 10.25 and your tag clearly says 10 2 - which means 10.25. I thought I would throw that out there and see if someone can help ID your axle. S415B and 10 2 don't seem to go together.
Could you post up a picture of the yoke on your pinion where it connects to the driveshaft?
Any other codes on the housing? BOM codes are casted into the actual housing itself.
Also there is probably a digit at the beginning of that second row, clean it off a little more and see what the digit is, I'm guessing it's a "4" or an "L".
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Senior User
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From: Havillah, WA
Yes that was directed at you. If it's a 10.25 the yoke is most likely different unless someone has changed it. The odd thing is that I don't show Ford ever made a S415B in 10.25 Ring Gear.
I looked it up as well and found the same thing that S415B was put in Excursions but I also can't find any mention that S415B is a 10.25 and your tag clearly says 10 2 - which means 10.25. I thought I would throw that out there and see if someone can help ID your axle. S415B and 10 2 don't seem to go together.
Could you post up a picture of the yoke on your pinion where it connects to the driveshaft?
Any other codes on the housing? BOM codes are casted into the actual housing itself.
Also there is probably a digit at the beginning of that second row, clean it off a little more and see what the digit is, I'm guessing it's a "4" or an "L".
I looked it up as well and found the same thing that S415B was put in Excursions but I also can't find any mention that S415B is a 10.25 and your tag clearly says 10 2 - which means 10.25. I thought I would throw that out there and see if someone can help ID your axle. S415B and 10 2 don't seem to go together.
Could you post up a picture of the yoke on your pinion where it connects to the driveshaft?
Any other codes on the housing? BOM codes are casted into the actual housing itself.
Also there is probably a digit at the beginning of that second row, clean it off a little more and see what the digit is, I'm guessing it's a "4" or an "L".
Postmaster
Joined: Aug 2012
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From: Westfield, Indiana
Ok so it is LS, that is what the L means. But I'm still stumped on why that tag says 10 2. Far as I know no Excursion came off the lot with 10.25 axles and no 10.25 Axle was made with the S415B as the axle code. Where is the number dummy when you need him? If it were me I don't know that I would trust that tag, it just doesn't make sense. Maybe someone smarter than me on axles will chime in and help.
Thread Starter
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Senior User
Joined: Oct 2012
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From: Havillah, WA
Ok so it is LS, that is what the L means. But I'm still stumped on why that tag says 10 2. Far as I know no Excursion came off the lot with 10.25 axles and no 10.25 Axle was made with the S415B as the axle code. Where is the number dummy when you need him? If it were me I don't know that I would trust that tag, it just doesn't make sense. Maybe someone smarter than me on axles will chime in and help.
Postmaster
Joined: Aug 2012
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From: Westfield, Indiana
You can't visually tell the difference between the two except the flange and the flange looks like the 10.5 on the EX - it doesn't look like the 10.25. But I'm sure not willing to say to you "it's for a sure a 10.5". I couldn't find the casting number you took a picture of so that was no help. That axle tag says 10.25 so I don't know. There is a guy on FTE his name is Number Dummy and he is a ford parts and axle guru. Send him a PM and a link to this thread, see if he can help you figure this out. I know if it were on my truck I would want to know for sure what is was, and what's inside it.