The current format of the Victorian number plates (1AA-1AA) provides an opportunity for both old and current AM radio station call signs to be printed.
Here’s a few I’ve found. Hope the rest of the Media Spy community can find some of the more elusive ones (I’m yet to see a 3AW, 2GB or 2UE for example).
8HA 900 - Alice Springs
Fiveaa 1395 - Adelaide
3XY 1422 - Melbourne (current and old!)