Why should all this parts sharing surprise anyone. Bertone and other Italian Carrozzerias are small companies producing low volume products. parts sharing is mandatory to allow production.
The surprise comes with the belief Exotic cars are special in every way with special bits designed and made specifically for it, fact and reality is, good designers are able to and are going share bits when possible. This allows the designs to see the light of day.
This is why the X1/9 IS an Italian Exotic, it meets every description of the definition, has the proper chassis-suspension design, dynamics and performance. Other than lacking power train performance and a race victory pedigree and social status brand identity it is one of the most important small mid-engine cars deigned and produced in Automotive history.
To this day, the x1/9 is treated as used tissue paper by much of the media and car folks. Example of how marketing drives brand identity and vehicle market values which is more often than not a perception rather than reality based on substance.
Bernice