Most of the recordings are from the 80s and beyond, and most of those are from commercial FM stations, but there are some older examples, of which I've listed three below.
The site also carries other radio-related content such as jingles and commercials, and it has a parallel Facebook page where the latest content is posted.
The Radio Antenna
AM stations 1950s-70s:
2SM 2UE 2UW Sydney, 2GZ Orange, 2NX Newcastle, 2TM Tamworth
3DB 3KZ 3UZ 3XY Melbourne
4BC 4BK Brisbane, 4IP Ipswich-Brisbane
Many other stations 1980s-2000s
John Vertigan on 3UZ Melbourne in 1967
Rod Muir on 7HO Hobart in 1967
Kevin Hillier on 4IP Ipswich (+Brisbane), c.1975
Other content includes
+ Many other airchecks from AM and FM radio from the 80s to the present.