According to Fuchs Australia website when I perform 'which vehicle - which Fuchs product' search facility, they recommend ATF 4000. (mine is ML270)
I also did a search for a different model with same transmission (ML500) and they recommend either ATF 3353 or ATF 4000 for ML500.
I've included the link I used.
http://www.datateck.com.au/lube/fuchs_au/default.asp
Now feeling slightly confused...