I was referring to the modern Cuervo y Sobrinos, but that one is pretty hideous.

Pretty much every vintage you find branded Cuerve y SObrinos is a redial at best, or a slapped-together mashup at worst. Redialers seem to think CyS was an actual brand, whereas it was usually a second name on the dial like Tiffany, Meister, Turler, Gobbi and countless other retailers. As for the "Unicos Importadores" part which frequently goes with CyS, it refers to the fact that CyS was the sole Cuban agent for the brand. It only applied to two brands, and I've forgotten what they are just now - I have to hunt around on one of the Spanish forums for the relevant thread.