I don’t know if the tubing manufacturer was so restricted but I do know the top of line Puchs in late 1980s were made in Italy by Bianchi. I had a Puch Mistral Professional and Bianchi Superleggera side by side (both brand new) at VeloSport in Berkeley and other than the pantographed Cinelli stems and fork crowns that were embossed with their respective brands, they were identical beneath the paint and decals. The Puch was significantly cheaper so I bought the Puch. I was always a little rebellious in a punk-rock way so I pulled off the decals and re-decaled as a “PUKE”