I was able to collect from the friend some info about the piece and its history.
It was made by order of the owner of the car as an original spare part, it was made in Turin in the seventies.
It was hand made by a specialist in vintage car restoration, using the original one as tamplete and after consultation of Alfa Romeo original drawing and documents to remake it the original in size and shape, plate material, thickness, screws size and length. There is no discrepancy it is exactly matching the original one.
The car was Castagna Alfa Romeo 6C 1750 GT 1931, and belonged to a friend of mine, it was sold few years ago.
Minor differences exist among all the “Alfa Romeo" "italic sign", fitted to the radiator of various model of Alfa Romeo in the thirties.
Car were not only manufactured by Alfa but often made by one of the many different coachbuilder, “Carrozzeria Castagna & C.” based in Milano was one of them. Even among the originals made by Alfa Romeo there are minor differences, because the factory did'nt use only one trimming die but more than one and were made by various artisans.