Ive have only seem them on polish cars so technically homemade
What was illegal about production?
This also answers blus question on if you can get them anymore
As far as probably all of you know the factory of Seicentos is located in Poland. But Fiat is not a producer of the rear lamps, they take them from smaller suppliers. The white lamps were produced by employees in the factory of the original ones, after the work, because of it in Poland we can drive with them, because they have all the signatures, homologation & etc. stuff.
I know that sounds like from a criminal novel or movie, but it was like that.
Concerning the second question, currently it is possible to buy them on the second hand market, but it is a pretty rare thing.