I wonder what is the oldest rail vehicle in (non-heritage/tourist) revenue service in Australia?

I believe (but haven’t confirmed) that it used to be the “Cafe 828” car in the Overland consist (RBJ3, 69 years old as of a few years ago) but that has since been replaced with another cafe car called “Matilda Cafe” (which I believe is a different physical car and not just RBJ3 with a new name, but I don’t know it’s road number)