The 881 dropout T-Mar speaks of was a predecessor of the later dropout that was ubiquitous on bikes like the Peugeot PX-10. Though it was drop forged, it was thinner than the later dropouts, 5 mm thick rather than 7. Even later, Simplex made dropouts (maybe only the short type in photos above, but perhaps also the long type) having a "Campagnolo" style derailleur hanger (compatible with Campy, Shimano, Suntour, etc.) rather than the proprietary one for a Simplex derailleur. I like the 881 dropout, myself.