The spool in 41110-30A90 fits all these models in these global markets as well:

 

This blog post details the necessary clearancing (if you choose this route, there is another option, but it requires a stub axle and some very quick work). I clearanced mine.

http://figsengineering.blogspot.com/...tallation.html

This is mine after clearancing - the black arrows show where the case was widened on both sides:



I was extremely careful to only take as much as necessary. The spool had to be clocked correctly to fit into the housing, even when frozen as you see in this picture. Tooth engagement did not change with the OS Giken install and the original snap rings and bearings. I only replaced the seals because everything else was still in perfect shape even after 250k km.

 

Nope:

...unless you've inferred that this spool can fit in the (I suppose) bigger diffs. N.B. - the 50031 looks backwards compatible with the 50030, according to the cross-reference, at any rate.

I suppose you looked up 41301-53040, since it is present in the ALE20L-AEFSYW config of the is220d (EU LHD spec). That's a different diff assembly (41110-53280, also present in 41110-53170, again on the is220d).

So, unless I'm missing something obvious, the issues are:
-there is no (confirmed) equivalent spool to the OEM open spool. Here's somebody that tried (one of my original references, along with the supraforums/mk4de/etc databases, my.is, all the info here... etc, etc).
-there is no (confirmed) high gear ratio final drive kit (>3.7) for the big torsen spools (IS-F/GS-F/etc... the Mark X GRMN is an unsolved mystery). edit: I've read about all the IS-F with IS350 diff swaps and etc, cross-referencing 42330-30160 (for example) gives it all away
-the small diffs (is250/gt86/etc) require a flange mod and a subframe swap
-the old diffs with bolt-on axles (supra/aristo/whatever) require modifying the old axles by machining out the ABS rings

edit 2:
Nope. The IS250 and GS300 share subframes. Everything else uses a different subframe.

Listing EU only:

IS250/GS300:


GS450h & so on sub:


EDIT #5000:


This is the Mark X GRMN.
GRX133-AETTH but modified:
https://toyotagazooracing.com/pages/...x/specs/specs/
...to GRX133-VMWBMT

The carrier assembly also matches up and... no time now, I'll dig through this later, but this is at least somewhat promising.

 

wow I have never seen so much diff info in one thread
thanks @lobuxracer and @Lwerewolf

 

@Peter Shen: Any long term issues with you diff swap? Still happy with the results? Thinking about doing the same with my vehicle.

 

You might as well ask any USDM/JDM gs450h owner whether there've been any long-term issues with his car. differential-wise... In my case - I can see why people can't seem to match the fuel consumption figures, took me awhile to get them back to what they used to be... if you know what I mean

 

Well that’s encouraging. I’m looking to use the diff from a 2008 GS350 - this should bolt on without issues?

 

GS450h Europe 3.27
GS450h NA is 3.76 same as LS430
GS350 diff is 3.76 same as LS430
GS300/IS250 diff is 3.91
GS300/IS250 AWD diff is 4.10
GS460/LS460 RWD diff is 2.937
IS350 diff is 4.08
LS460 AWD diff is 3.13
LS600hl AWD diff is 3.92

source Car-Part.com

 

I'd check the diff regardless, there CAN be further differences.

LS600h EU-spec is taller, same with the GS.
IS250/GS300 won't fit the GS450h subframe - you can change the subframe and diff flanges and whatnot if you want easy access to a torsen, not sure if it's going to blow up with the 450h - look up how boosted high-torque GT86's fair with their stock torsen, I have no clue but that would be the best indication.

Newer "big subframe" diffs need a pumpkin cover swap or a rotation of one of the stock subframe bushings - read the whole thread, practically everything is in it.

GS350 ought to just bolt on...? (same as post-technical refresh LS430 & SC430)

 

3GS differentials bolt right in.
No issues so far, it's basically an OEM configuration, the car is overall much nicer to drive, no downsides unless you need the 270kph top speed.

The next thing I'm thinking of is the 4.08 from the IS350, as I'm running oversized tires.

 

Anyone know what size options can the 2013 GS350 use? It is the only 4th Gen that has the 6speed Trans in RWD. I thought I saw it had a 3.615?

So I run a slightly little taller profile higher sidewall 19" tire. I would like to get a little more low end acceleration. I looked and it looked like the SC400 diff's were a direct fit at 3.92 & 4.08. Would this be correct? Seems there are some diff experts here. Thanks.

 

Funny. The 3.615 is the EU-spec LS/SC/GS430's diff ratio, probably the same pumpkin with a different back cover (for the 4GS's two-bolt bushing orientation).

See above - looks like the easy options are the 3.769 and the... 4.10 or whatever the 2nd gen IS350s use. LS600h if it's available (no clue how often those pop up). again, to reiterate, since people from across the world are reading this - diff ratios differ across regions (JDM/US/World/etc).

SC400... if it's the type of pumpkin that fits and if the diff has the big flange (can swap that but still), you'll need to swap the axles and modify the swapped ones (machine out the ABS ring - our cars have it all built into the hub)... or so I've read somewhere without digging in too deep - proceed at your own risk. Does mean that torsens are way easier to acquire if you go down that route, though.

 

Thanks for the help all. The photo attached relates to the (allegedly) Japanese GS350 I’m looking to take the diff from. The model code seems to differ from the ones listed in this thread, which has me scratching my head.

 

GRS191 is the code for the GS350 RWD. GWS191 is the code for the GS450h.

What's with that vin plate O_O

 

I’m based in NZ, so the VIN plate is added for imported vehicles (we get a lot of Japanese imports into the country).

And now for a confession. I don’t actually have a GS450H, but rather a GWS204 Crown Hybrid - not that there are many differences mechanically it seems. Unfortunately Toyota decided to throw the 3.2 diff into the Crown hence my desire for a differential swap out.