T+3 was implimented in 1999. Prior to that it was t+5.
At the time it also had a lot to do with seller delivering evidence of the secutities, certificates or SRN notices.
Probably could be updated now.
http://www.asx.com.au/about/shareholder/media_releases/MR270199_AS3.htm
https://www.abnamromorgans.com.au/download.cfm?DownloadFile=93A1D3CD-D60D-540D-6DF66E2230BA3B45
