The fork ends and rear dropouts are stamped. The Gran Tourismo was (if I read and remembered correctly) a cross-over model from mid- to high-end. It had the 3-tube Columbus butted tubing, but not the forged dropouts.
I wasn't sure originally how to deal with a lack of derailleur hanger.
Many thanks to
beicster for setting me up with a hanger, officially the first part for my frame-up build!