David, reliable information seems to be hard to come by.
RM 28, later renumbered RM 16 is the only fleet number that appears in a search, including Crossley. The odd thing, that was an Inspection Car/General Manager’s personal car. It was an International truck chassis with a Napier car body mounted. Queensland Rail bought a number of petrol powered AEC truck chassis, that were converted to rail motors. Most of these were later converted to Gardner power.
By the mid 50s to the 60s, the Red Rattlers (RMs) were superseded by the 1800 class, stainless steel with royal blue trim front and rear, 1900, stainless steel with royal blue trim front, rear and sides and 2000 class, polished stainless steel.
Is it possible that your charabanc was operating on the 2’ gauge, cane train network?
We’re you working at the Farleigh Mill?