If you download my bbc_cont.zip from train sim you will find a collection of containers including 2x20ft.
You can either repaint the ace files or paste you own textures over them.
Instructions on how to position them are included.
The included wagon in probably unlike any aussie wagon but TSM files are included if anyone wants to play around with it.
The same wagon with a large collection of international containers in on UKTS file 15633
To use these, reposition them with Shape File Manager and add this line to your wagon....
This one is NOT included.

FreightAnim ( ..\\Common.Loads\\45ft_Conflat\\2x20ftContKline2.s 0.0 3.0 0 )