....I believe I can positively identify which line 8179 & friend were on, and which way they were headed at the time....
I had an idea that I might have taken the pic on the Banko, somewhere between Belmore & Marrickville, and was standing on the platform of whichever station, looking at a train on the Metro Goods line - hence my rejection of flathog's guess of Guildford (which is wrong anyhow, but that's by the by). Sorry if this led you all on a big guessing bumsteer
has identified the surroundings beyond a doubt, they all fit. Mortdale Bowling Club, the Boundary Rd overbridge, it's all so clear now
I was standing in the little "recreation area" (that you can see if you look up at the right moment as you pass by in the train between Mortdale & Oatley) just below the booker-on's office at MMC. yobboford is also correct in stating that the freighter is on the Up.
Over to you, yobboford - and thanx for filling in the "memory blanks"