You guys all seem to be referring to machines from the later years, probably because you are younger than me, but back in the olden days (the 70's) pinny parlours were packed out and you had to put your 10c or 20c on the glass in a queue just to get a game, so my theory is that the best money makers were old EM machine's simply because the games were more popular and the machines more prevalent. As well as dedicated pinny parlours, just about every takeaway shop had 1 or 2 and they were always being played. But I have no idea which machine it would be.