2004 Rear Diff ???

[my pos mounty]

Limited slip differential with the wrong differential cover. Your cover is off an open diff (with the notation for 75W90).
Third gens with the hitch from the factory had limited slip rears.
Also the tag states 3L73 88, LSD with 373's with an 8.8 inch ring gear.

 

[my pos mounty]

If you have an open you should not be able to turn it.

That is incorrect.
Only way it would not turn is if someone opened up the diff and welded the spider gears to the carrier. Not likely in this instance.

 

[Ronin8002]

You are right...thank you for clearing that up. After I posted it I thought that might be wrong but could not really visualize why. I must have been thinking of the way a mini spool works when I posted.

 

[EasyRhino]

Limited slip differential with the wrong differential cover. Your cover is off an open diff (with the notation for 75W90).
Third gens with the hitch from the factory had limited slip rears.
Also the tag states 3L73 88, LSD with 373's with an 8.8 inch ring gear.

Missing door tag and this discrepancy indicate some undocumented changes.

I would take nothing for granted in this Ex, unless I could verify it (as you are doing).

 

[grof]

Missing door tag and this discrepancy indicate some undocumented changes.

I would take nothing for granted in this Ex, unless I could verify it (as you are doing).

i bought Explorer on Public auction, it was Repo.

only paperwork i got was a Title

 

[my pos mounty]

And the ONLY way to know for sure would be to open up the diff and look inside.

In my opinion, it would be doubtful that someone changed the ratio. They would have had to change front and rear at the same time. While that is possible, if it was a repo and not a wrecked/rebuild, it is quite unlikely.


To the OP: What is the purpose of the questions?
If it is to change your diff fluid, you can use the Lucas synthetic 75w140 on both differentials without an issue. If you have the LSD, the Lucas will not need the additional friction modifier, or at least it never did in my LSD's, my current F-350 included.