I think you are confused or mistaken about what you want to do.
The larger axle T series diff (late model AE86 - Japan and USA only) does not exist in Australia except for the very limited few that are imported.
The only reason you want a T series AE86 center is because they are LSD, and if you are buying one get the Zenki (early) one as it will fit in a T18 diff with the same axles.