The "Southern Aurora" consist also included lounge and dining cars, together with a deluxe sleeping compartment in one of the cars, but the train only accommodated sleeping berth passengers. Using the 'norm' for passenger trains in NSW, no second (economy) class sleeping car travel was offered by the "Southern Aurora"; neither was sitting accommodation.
So, for anyone wanting to travel on the "Aurora" it meant paying for a first class berth.
"The Spirit of Progress" provided the accommodation for first-class sitters, second (economy-class) sitters and a limited amount of first-class sleeping accommodation by means of an NAM first-class twinette sleeper included in the "Spirit"'s consist.
The NSW Railways had dabbled in second-class sleeping cars on a number of occasions, but these were shortlived ventures using old rolling stock (such as out-of-date AL Pullmans on the North Coast line). The closest the NSW authorities ever got to serious long-term second class sleeping car services was the design of a SAM type version of the standard TAM first class sleeping cars, the SAM having nearly twice the number of berths within the same basic carriage dimensions as the TAM! The back-packers' version of the TAM! No SAM was ever built!
The first westbound run of the "Indian Pacific" on 23 February 1970 may have mislead observers, as it was not typical of the standard "I-P" consist. On that inaugural run, the "I-P" worked as two trains for as far west as Port Pirie before amalgamation. The first train conveyed first-class sleepers, the second train included the second-class (economy-class) sleeping cars.
Fortunately, we have that initial consist recorded by the authors of "Coaching Stock of the NSW Railways - Vol.2" (Eveleigh Press, Sydney, 2002); on page 243:
1st train - Locos 4601 & 4602.
HGM.204 power/brake van.
ER.210 dormitory (crew) car.
ARL.249 first class twinette sleeping car.
ARL.247 first class twinette sleeping car.
ARJ.241 first class roomette sleeping car.
CDF.266 cafeteria-club car.
DF.264 dining car.
AFC.239 first class lounge car.
ARJ.240 first class roomette sleeping car.
ARL.261 first class twinette sleeping car.
ARM.253 first class twinette sleeping car with deluxe compartment.
ARM.252 first class twinette sleeping car with deluxe compartment.
SSA.260 special service car.
HM.259 brake van.
2nd Train - Locos 4603 & 4604
HM.257 brake van.
ER.2O4 dormitory (crew) car.
BRJ.214 economy-class twin-berth sleeping car.
BRJ.218 economy-class twin-berth sleeping car.
BRJ.215 economy-class twin-berth sleeping car.
CDF.229 cafeteria-club car.
DF.235 dining car.
AFC.236 first-class lounge car.
ARJ.242 first-class roomette sleeping car
ARL.262 first-class twinette sleeping car.
ARM.251 first-class twinette with deluxe compartment.
HGM.202 power/brake van.
Obviously, these trains were carrying some carriages which would become spares held at Perth when the first run arrived there.
The normal "I-P" consist at the start was HGM. ER. BRJ. BRJ. BRJ. CDF. DF. AFC. ARM. ARJ. ARL. HM.