Since the Adelaide Route started a few years ago it almost always had the older 777's A6-ECx and occasionally A6-EGx aircraft but never the newer ones, but as of a few months ago it almost always has the newer ones with updated J class A6-EPx and A6-EQx.
Not sure what prompted the change as ADL would most certainly not be a high profile route. They still do on rare occasions send the older one's however.