Here, what I found in the books.
These are 170 mm light units, sometimes called the '4300' type (or series) from Carello due to the design of the glass.
They were made as an alternative ( upgrade) for the normal bulbs to the Halogeno H4 bulbs and they were firstly mentioned in the 1972 catalog. So in terms of the history of Carello, they were already a later Carello production , meaning: in fact to late for the Giuliettas, however they have the same attachments as the light units on the 101 cars indeed, and probably compatible with the 750 Spider too, but I never tried that.
Over the years, I noticed that some of the really late
produced Carello units did not have references at the back of the reflectors anymore, although they were often still in their sealed original Carello boxes . See example below.
As mentioned by Andrew, the ones in post # 1 show the logo and blockletters at the 7-8 o'clock position. When looking with a magnifying glass, I can see the # 4300 under that logo.
Other lenses for the same 'family ' of light units carry the # 430 .
What makes it difficult to determine whether they are original Carello or reproduction is that many of the reproduction units do have the Carello logo and name on the lenses. I have no idea how they managed to do this legally.... I doubt that the repro units that are for sale now on the market have used glasses, maybe they bought a remaining stock of lenses from Carello ( Marelli) ? ... or maybe they made their own replica from the original lenses, I can only guess what happened. At the start of the reproduction, years ago, one could easily see and feel that the reflector was a reproduction. Now, finishing quality has become better.
So these light units could be original or might be reproduction indeed. I would vote for 'original' because of these lights being of the later type. I've seldom seen earlier original units, not having references at the back, although they do exist.
I don't know exactly when Carello was incorporated by Marelli but maybe the lack of references at the back of the reflectors could be related to that action.
Because of the little position light they have inside, I would guess that originally, these lights had the Carello order number 03.915.816 for the complete unit, that number was marked on the paper seal of the original box. These ones were initially for the German marked as mentioned by Divotandtralee.
The 03.485.816 were listed for the European market but one could buy a special set of them, the 05
.485.816 , for cars that drive at the 'wrong side of the road' good heavens !
Carello sold them as the Halogen Universal Conversion light units.
Fiat used them on some of their cars and commercial vehicles but they also appeared on other brands too: Honda, Lotus, MG, Morris, Triumph, Skoda and Volvo. I also found them listed for the Lancia Stratos and the Ferrari 308 GTB.
And what about Alfa ?
It is only starting with the 1980 Carello Catalog that they were mentioned as the halogen conversion for the traditional light units from some Alfa 105 series cars too.
Due to their contruction, they were only suitable for Alfas having one light unit at each side of the car, so where low and high beam were combined in one unit: Giulia Sprint GT, Spider Junior 1300 - 1600 and the 1750 - 2000 Spider Veloces.
One word about the design of the 4300 glass, when looking for a light unit, always pay attention to how the unit is attached in the car because that type of glass was also used on other light units as can be seen on the next pictures, showing a light unit for 105 Alfas that had 4 light units at the front. The same glass but totally different in terms of the attachment to the car.
You can also see the lack of a reference on the back of the reflector on the unit of the picture, although it is coming out of the original sealed Carello box when I bought it.
The last picture shows a later unit, also for Alfa and still with the Carello name on the glass, but it is packed in its original Marelli
box. The reference is on a sticker now.