Not sure about why they have changed it but my cousins were on the flight and were very happy about getting a Intl config aircraft on the sector, also said it was a very bumpy departure out of SYD

Would have thought maybe Grand Final demand, maybe lots of people flying out of SYD due lack of seats out of MEL?

not 100% sure, but a 332 operated some SYD-MEL flights yesterday replacing a 763 on some flights. Maybe a 763 went u/s, and the Perth 332 was used as a replacement?

Maybe the 332 that was used for the AFL Grand Final flyover was then used on the scheduled MEL-SYD runs that day in lieu of a 767 seeing as they had the aircraft there already?