The listed coordinates take you to the old ambulance station, built in 1904. Today it is not used as an ambulance station anymore, but the Royal Flying Doctor Service still holds their clinics in the building.
You will find the cache at:
S20*05.# $ @
E146* 53.@ # #
For the missing numbers in the coordinates you just need to answer the following questions and do some math:
A:How many feet was the guy lifted off the ground, who was struck by lightning?
B:And how old was he when he finished school?
C:How many sides (glass panes) does the lamp have that hangs above the door of the ambulance station?
D:Behind the ambulance station you can find the remains of Harry Bowrey's 19_8 mine.
E:How many gentleman are in the photo taken in front of the ambulance station in 1906?
# = B - A
$ = A + D
@ = C - E