Even though NYC law requires either a valid CO certificate or a "Letter of No Objection" from the Dept of Buildings to be submitted at closing, I never saw one. A housing court judge was quoted as saying, "it is more likely that you will see a yeti crossing the West Shore Expressway wearing a Mets hat than a final certificate of occupancy at a closing."
That's why I was semi-thrilled to find the original CO for this place. I wasn't expecting to find it in the city archives but there it is. Apparently, even though COs weren't mandated at the time, if you did any work to a building which required a building permit, your CO came with the successful inspection report.