Slightly off topic..... I had to deal with the foreign lightweight stuff when I worked at the bike shop in the 70's
Nightmare as they had importers (Elsmar), Distributors (Holdsworths), people who did both (Chicken and son, Ron Kit) plus reps who seemed to get stuff from anybody they could LOL. Not knocking the reps as I have some 70's unbranded nice kit.
Anyway, UK frame suppliers seemed pretty anal about numbers stamped on frames as that is what we paid them against......not so anything from abroad (Italian, French, Spanish) who never seemed to actually make or do anything in August.. It's like the whole of europe shut down for a summer holiday. !!
Imported Frame numbers were always hit and miss and when slotted bottom brackets started I just think they could not be arsed to find somewhere to stamp a number.....
Shaun