Preemo & Bosi72,
There's a German forum which seems to be pretty good at solving historical queries like yours:
https://www.vielfliegertreff.de/foru...n-suche.84975/
It starts out predominantly in German, but in later years, English requests seem to get more common. Feel free to send me a private message if you want something translated, though.
There's patchy ACARS data going back to the early 2000s in various locations. Bosi72 - QF10 appears to have been operated by VH-OJR on 11 March 2003, and -OJQ on 13 March 2003, but there's no data for the 12th. Having said that, if you arrived in Melbourne early on the 13th, then the QF6 and QF10 flights probably left Frankfurt and London on the 11th rather than the 12th.
Happy hunting!
-Carl.