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Ive got a R160 that I need to identify properly before I sell it. The part sticker (which could have been swapped) on the backing plate says Viscous LSD gear ratio 4.444. Pulled it apart, confirmed from the stamp inside 40.9. Stubs are not present, but inside the carrier are 23 spline, both sides, female. The VLSD carrier is the Type 1 unit 4 pinion gear unit. Its very different to the VLSD Type 2 unit. Type 1 looks large, sort of like a CLSD where as Type 2 looks like open diff unit.

When I had the part number run, it came back as JDM Auto Legacy Turbo, but still unsure. Looks to run short, unequal length stubs which are not present.

If what I can find on the net is to be believed - "Third LSD in is from a 91 legacy SS but also came from some JDM cars and the SVX (however the svx uses a different spline count on the axles and is completely incompatible with a impreaza as far as I can figure out) These are a viscus unit too however they have 4 pinon gears which makes them much stronger. This and only this diff uses the axle with two sets of splines".

Looking for feedback from someone who knows what they are talking about.

Will try to include pics. Thanks in advance.

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What you've said is spot on. This requires unequal length axles or stubs to access the "LSD" part.

Will work in any older Subaru with the appropriate axles and 4.44 transmission.
 

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I should have added that no axles are present with my unit, but looking in from either side - it has asymmetric female spline 'sockets' inside - would accept male 23 tooth on the left, male 17 inner and 23 tooth outer on the right, so would need the asymmetric axles with a dual-spline on the right. Pics attached of the right side view down the diff and also a pic of axles - Id need the one on the right of the 2nd pic, correct? Does this strengthen my belief thats its an early Legacy RS or SS Turbo unit rather than latter WRX or WRX STI?

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You do need the axle on the left to make use of the VLSD part of the diff, and a conventional axle for the other side. A friend told me you could use conventional axles on both sides, and it would function as an open differential, but I haven't personally tried that. Your exact diff may have came from a Legacy/Liberty RS, but that style was common on the WRX gc's as well.

Here's a pic of the (1991 only) Legacy SS diff with the unequal length axle stubs. Works the same as the asymmetric axles, but the one longer stub is long out of production. If you can find a liberty RS with rear factory VLSD, it should have the same stubs.


The stub on the right in your picture corresponds to the "normal" stub (part #11). You would still need the longer stub (part #10) for the VLSD part to work.
 

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You do need the axle on the left to make use of the VLSD part of the diff, and a conventional axle for the other side. A friend told me you could use conventional axles on both sides, and it would function as an open differential, but I haven't personally tried that. Your exact diff may have came from a Legacy/Liberty RS, but that style was common on the WRX gc's as well.

Here's a pic of the (1991 only) Legacy SS diff with the unequal length axle stubs. Works the same as the asymmetric axles, but the one longer stub is long out of production. If you can find a liberty RS with rear factory VLSD, it should have the same stubs.


The stub on the right in your picture corresponds to the "normal" stub (part #11). You would still need the longer stub (part #10) for the VLSD part to work.
Thanks for that. I had seen that picture. Id really like to know the teeth count on those short axles. My diff would need 17 and 23 on the dual spline side and 23 on the other side. This does not match any of the descriptions here:

jared's school on rear diffs, axles and splines:
there are at least 6 setups
on the diff side:

22 splines - early diffs and non LDS diffs .. identifiable by single large flower looking nut on side of diff assembly pict
25/20 splines - early jdm LSDs -identifiable by plate and 5 bolts on side of diff - 3 sets of teeth are visible if you look through the diff axle is dual spline axle has tapered end and spirals befor the splines pict,pict
25/19 splines - early jdm LSDs -identifiable by plate and 5 bolts on side of diff - 3 sets of teeth are visible if you look through the diff most likely from a earle JDM legacy 89-99 pict
25 splines - later diffs and LSDs -identifiable by plate and 5 bolts on side of diff
outtie - has a male spline setup on diff (89-93? legacy turbo only) look like front axels pict


So, from this I think I may have the "outie", but the short male/male stubs in your picture are missing. Would need teeth count of an "outie" to confirm.
 

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Hmm, I'm not too sure. If BC/BF/BJ turbo differentials don't take the assymetrical GC axles in place of their stubs, that's news to me. TBH from owning 2 cars with that type diff from the factory, that diff sucks! 30 years from new it makes almost no difference. The torsen type from the early 00's GD WRX's was way better at limiting slip, and way more fun in the dirt. AND they take the same axles as normal subarus (equal length ones from regular 2nd gen imprezas and legacys). CLSD/plated diffs are great too but they wear out, and make your car sound broken on sharp, slow turns.
 

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Discussion Starter #7
No doubt but I need to be sure what I have to make sure Im honest when selling it or accurate when looking for parts. I wonder if anyone can confirm the spline count on an "outie".
 
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