Sorry... we cannot have this....Americans solving Australian Postmarks!

Bravo! Postmaster.
My colleague shall be delighted. (He whom snorted, when I suggested the 3rd letter was an "L")
Please accept bragging rights.
"Wal Wal PO 7/3/1887; closed 30/1/1981"
From the internet:
FWIW - there is a Wal Wal listed in Freeman & White as a railway station. Opened 7/3/1887, S. East of Murtoa, 270km S.W. of GPO.
Author "Traralgon 3844" (In 2009)
Many small 'Post Offices' in towns like WAL WAL were run out of a spare room at someones house. You didn't need to handle much mail to be declared a post office in the 30's. They were also the local telegrapgph office.
Some did not handle enough mail to be designated a Post Office. They did handle the local telegrams and were designated Telegraph Office and in many cases handled small amounts of mail. In this case the Date Stamp would have read T.O. WAL WAL.
When the were upgraded to a Post Office they were generally given a new date stamp. In the meantime the old Date Stamp had the T.O. burnished off. That is the most likely case in this instance unless WAL WAL started off as a Receiving Office and then the Date Stamp would have read R.O. WAL WAL.
The Railway Stations usually had the R.S. after the name.
Similarly in later years the suburban Post Office date stamps had the S.E.6 and the like burnished off when the changeover to Post Codes was taking place. You often find post marks with a blank area after the name.