Ahhh... Yes. The old Melbourne dog boxes. They withdrew those in the mid 70's after serving the Melbourne metro area for about 60 years. They were originally converted and extended from just the passenger carraiges that were steam hauled before electrification of the Melbourne system. I have a 3 car set (kit nearly completed) that will run around Garahbara. Note the last two trailing cars. They were not used on the suburban system, but were used on country hauled services for about 50 years, before scrapping them. They scrapped the dog boxes as they had outward swinging doors and were considered too dangerous for heavy passenger use with the doors being opened by passengers before the train had come to a stop. The dog boxes were a different generation of train to the "tait" ones (my colour pic above) as they were built as electric from scratch, were wider, and had sliding doors. The Taits cam into service in the 20's and 30's, and the last ones were finally withdrawn from service in the mid 80's.
The trams are still used (in an overhauled sense) around the Melbourne system.
Bob, provided Puffing Billy is steam hauled, it will be the "older" Puffing Billy. The Melbourne suburban train services will take you right to the Puffing Billy station. (27 stops, 65 mins).
What are the dates for your XPT bookings?