This would have been a dealer installed option, along with painted or taped on pin stripes, which were often added to the cars (I’m sure for a nice price to the customer). Not from the factory in any year.
Yes, they are on my car also (’90 from Italy). On the drivers side that is. The ones on the passenger side I got from the dealer a few years back and still need to fit them.
I have only seen them in the US on a few cars, so I don’t think they were standard on all 780s. I have a photo of the cars in the factory and I think the answer may be that those with the black turbo grill did not have them and the 780s shipped with the chrome grill, 6 cylinder model in the US. I can see models sitting next to each other in the final inspection area of the factory with both. The B230FT turbo 4 from 1989 to 1991 did not have them in the US. I’m not sure how the engine/chrome decisions were with the European models diesel etc.. Interesting to see this. I will also inquire with my contact who was at Bertone to see if he has any other information. I know my 1991 also had pin-stripes which were a dealer added “option” for sure in the day.