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Discussion Starter #1
I need to replace thr rear diff and driveshaft on my 2005 Outback. What can I use? Can I buy a rear diff off a 05 legacy Gt?
 

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As long as the gear ratio is the same yes on the diff. If you mean the drive shaft from center diff/trans to rear diff, no it is not interchangeable. It needs to be an outback driveshaft.
 

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It's a mess.

According to the 2005 FSM, it's 4.444 final reduction on the Outback XT 5MT and Outback 2.5i 4AT, 3.583 on the Outback XT 5AT, 3.272 on the H6 Outback, and 4.111 on the 2.5i 5MT.

None of the Legacy ratios match the Outback XT ratios, but the Legacy Turbo 5AT matches the Outback H6, and the 5MT and 4AT match the Outback 2.5i 5MT.

So an Outback XT 5MT can maybe use a 2.5i 4AT diff, which there should be lots of, but for an Outback XT 5AT, there's no other option among the 2005 Legacy/Outback models.

Looking at the diff assembly for the manual XT on a dealer parts site, there are compatibilities with earlier and non-outback models. Best bet is to look up a new one there for your car and look at the "what this fits" page. E g. https://parts.villagesubaru.com/p/Subaru_2005_Outback-25L-TURBO-5MT-XT/DIFFERENTIAL-ASSEMBLY-REAR/49501245/27011AA542.html

It doesn't look like there's an equivalent new differential for a 2005 XT 5AT available though (at least on my local dealer's parts page) so I can't offer a link for the 5AT.
 

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So I'm just curious, what are the symptoms or problems you are having that has resulted in a diagnosis of replacing the driveshaft and rear diff? The driveshaft I can see as it's really not servicable and those carrier bearings do go bad. But I'm curious as to what's up with the diff.
 

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As @dyqik pointed out, the OB ratios can get messy, since it depends on your transmission (as does the driveshaft).

5EAT is OBXT only. 5MT is 4.444 (which is pretty common for OB and Forester), but the OBXT is also a VLSD.

Driveshaft is compatible from 05-09 OB only (and of course transmission specific). Legacy driveshaft has the wrong carrier bearing.
 

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Discussion Starter #8
Thanks guys. Reason for replacement is driveshaft is cut right after the center bearing. It broke at the back at the diff. The diff I was told was no good not exactly sure just told it broke and shaped the driveshaft. Right now car is driving in FWD. I got this car really cheap due to these issues.

Might just get the diff rebuilt if I can find someone that does it cheap.
 

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Haven't driven much. Why would I need a new tranny and from diff they are operating fine
The system will theoretically detect slip and possibly keep trying to lock up the center diff clutch, which can burn it out. That's from my understanding on how these transmissions work. Not the front diff but the center that sends power to the rear.
 

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Discussion Starter #13
The system will theoretically detect slip and possibly keep trying to lock up the center diff clutch, which can burn it out. That's from my understanding on how these transmissions work. Not the front diff but the center that sends power to the rear.
Got about 1000km driven with just fwd. No codes no issues.
 

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The system will theoretically detect slip and possibly keep trying to lock up the center diff clutch, which can burn it out. That's from my understanding on how these transmissions work. Not the front diff but the center that sends power to the rear.
Shouldn't putting the FWD fuse in disable the center diff?
 

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Discussion Starter #17

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Think I found a rear diff. Ratio is 3.272
Any confirm this is the right one. 05 Outback XT 2.5T it's the 5speed trans
It is not. The OBXT 5EAT uses a 3.583 ratio. AFAIK, it's unique to the OBXT. The 3.0L and LGT use the 3.272.
 

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I would just get a driveshaft and install it. The rear diffs rarely fail and nearly 100% of the time I hear "bad rear diff" it ends up being something else. It's usually a mis-diagnosis or poor assumption. Granted it sounds like you've got some awaeomse carnage so who knows.

But used diffs are usually really cheap because they never fail so it shoudlnt' cost much. There's no good way to rebuild these - you might as well just get a used one and be done with it. Like i said they almost never fail so just do what's cheap and simple here.

They typically don't drive normally without the driveshaft, that's odd. Cutting or giving (year dependent) power to the Duty C and "lock" it in 4WD which without the driveshaft installed makes it a useable FWD vehicle. I wonder if someone did something.

Does your AT light flash 16 times at start up or otherwise show any check engine or dash lights at start up or driving?
 
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