It certainly isn't common these days to see CRT 30ft aluminium containers however on today's BM4 service, there were no less than 3 wagons worth.
These boxes can be a pain to handle as you need wagons that can handle 30ft containers. As you will see below, there was a mix of wagons used.
CQBY 2162 is a third series CQBY from Rail First. These were build for maximum flexibility in loading and have a lot of pin positions. CQBY wagons were heavily used in CRT traffic in the mid to late 2000s.
CQGY 549 is unique in being one of only three of 75 CQGY wagons painted in light blue for CRT. CRT never took up the lease on the CQGY wagons which was being negotiated around the time of the Cargo Sprinter. Those with a good memory will recall the Cargo Sprinter trialling with light blue painted VQCY wagons. The CQGY wagons can handle 30ft containers as they were designed to handle the CFCLA 30ft grain containers (of which there were 24).
RQGY 35017 is a long term 30ft capable wagon, being converted back in the Freightrail/Freightcorp days to handle CRT traffic between Yennora and Altona. 4 x RQGY wagons were sold to Ettamogah Rail Hub (owned by the former owner of CRT) for 30ft traffic but they haven't entered service.
Enjoy!