If you want a brand new torsen diff but not the expensive original OEM you have an alternative torsen too much more cheap (about 400 USD).
The rear differential of the IS200 It's a F series, 7.5" ring size, like a front diff LandCruiser 90, and Detroit Locker make a Truetrac 911A342, a torsen diff.
You can see this post: http://clublexus.eu/foro/viewtopic.php?p=3995
Also I saw in the LOC a post about axel's code and I would like to add to things that I have been finding out:
A01A/B --- 4,100 ratio gear no lsd/LSD
A02A/B ----4,300
A03A/B ----3,909
The first digit A denote F series, 7.5" ring size, diff in the GXE10/SXE10, as Supra mkII, Cressida, Crown, etc.
in the IS300 JCE10 the first digit B denote G series diff, 8" ring size, that G series as Supra MkIII perhaps the carrier be swap it. The second an thrid digit denote ratio and 4ht digit denote lsd or not lsd.
That's all.
Greetings.