I went to my local Mitsu spare parts to see if they were still selling ATF SP3.
They were aware of this "rumour" for the last 6 months.
However, were still ordering and getting stock without any problems in 1L or 5L bottles or 60L drums.

Just the same I bought 3x5L bottles so I can refresh the ATF in the KS.
Was $50.40 per 5L bottle.