@GAD : I already got a reply from ABM's Sales & Marketing Director. He said they don't have them in inventory anymore but it is one with M6 thread. Since they didn't do this whammy bar entirely inhouse they had to order the cut to length material with the M6 thread from an external supplier and their minimum order size was 500 pcs. Later ABM bended it into shape. To re-install the bending tools at ABM a similar order size would have been required. Since demand was extremely low they had not reissued this bar anymore so far. (but in theory they could).
He pointed me to StewMac which would have a very similar one:
Slightly larger in diameter than the "traditional" tremolo arm, these arms are similar to those found on many imported guitars.
www.stewmac.com
Also a German company has them:
Tremoloarm mit M6 Gewinde, zum Schrauben. Farbe: schwarz.
der-trashcontainer.de
Ralf