Yeah, yours is a Mode A/C transponder, Moneybox.
advisory-circular-91-23-ads-b-enhancing-situational-awareness.pdf
This CASA Advisory Circular (updated a year back) is pretty informative and shows the regulator's current thinking about ADSB gear for the VFR mob.
A possibly relevant bit:
"4.4 About Mode A/C Transponders
Mode A/C transponders are obsolete technology that have been replaced or are in the process of being replaced in most parts of the world by Mode S transponder technology.
Australia already requires IFR aircraft to have a Mode S transponder as an essential component of ADS-B OUT equipment. For VFR aircraft, there are circumstances where a Mode S transponder is required, specifically:
for operations at major capital city aerodromes
for aircraft manufactured on or after 6 February 2014
where a VFR aircraft is modified by having its transponder installation replaced.
Aircraft owners who continue to use an older Mode A/C transponder should be aware that older transponders may appear to function correctly and be able to pass routine pressure altitude encoder testing, yet be unserviceable because no longer meets the full performance requirements. For example, CAO 100.5 and airworthiness directive (AD) AD/RAD/47 identifies that transponders using electron tube technology (such as cavity oscillators) may suffer from reply pulse anomalies as the components age. The CAO or AD (as applicable) requires periodic testing for such anomalies and, if detected, requires repair or replacement.
Since the cost of repairing a transponder by replacing its cavity oscillator is significant, the cost-effective solution is likely to be replacement transponder. In this case, a Mode S transponder is the logical choice. "
Also, a search of this site will turn up heaps of (locally oriented) discussion on transponders and "conspicuity devices" such as SkyEcho2s