Yes I did read Frederick T's digitised WW1 file on the NAA website. No injuries noted on his file
http://recordsearch.naa.gov.au/NAAMedia/ShowImage.asp?B=1817504&S=4&T=RDeath
JONES Frederick Thomas
Father Thomas Mother Phoebe UNKNOWN
At Mildura 47 years 1933 Reg#12987
David I can only transcribe information available from the death indexes. Are you sure he is actually buried at Avoca and not Mildura? His name is on the headstone but as you mentioned, perhaps memorialised only.
http://www.rootsweb.ancestry.com/~ausvsac/Avoca.htmFairly expensive to transport bodies even in the 1930's and Avoca is not on the main rail link to Melbourne from Mildura....and they had been having financial problems only 4 years prior to his death. Aren't you curious to know what he died from? I like to know what caused my ancestors' deaths....all adds to the family history. The certificate would also give his usual residence at time of death.
Perhaps his age was taken from their marriage cert and people are not always honest with their ages...especially when marrying a younger woman. He was born 1883 and Ethel 1899 so when they married in 1922 he would have been c39 and she 23. Perhaps he dropped a few years of his age

Birth
HARDY Ethel Elsa Evylan [sic]
Father James Brewer Mother Margaret Jane PEACOCK
At Moonambel 1899 Reg#20725
Australian Electoral Roll -
1909
JONES Frederick Thomas 27 Cotham Road, Kew Cutter
1924
JONES Frederick Thomas 37 Lemon Avenue, Mildura Tailor's cutter
JONES Ethel Elsa Evelyn 37 Lemon Avenue, Mildura HD
1931
JONES Ethel Elsa Evelyn 90 Peel Street, Kew HD
JONES Frederick Thomas 90 Peel Street, Kew Cutter
1936, 1937
JONES Ethel Elsa Evelyn Leibig Street, Avoca HD
1943
JONES Ethel Elsa Evelyn 174 Bank Street, South Melbourne HD
1949
JONES Ethel Elsa Evelyn 1121 Nepean Highway, Highett HD
1963
JONES Ethel Elsa Evelyn Leibig Street, Avoca HD
Cheers
Cando