The year this episode aired (1975) the New York City Police Department laid off 5,000 officers, out of a total of about 30,000 officers (16% of the force). From July 1975 until November 1979, no police officers were hired or trained in the City of New York.
At the top of the show, Barney announces that Wilson, Deluca, and Feldman have been laid off. Wilson was the name of a detective who appeared twice in season one (including the pilot) and had then disappeared. Deluca was the name of a detective who appeared six times beginning in season 5, so apparently was hired back on after the lay offs. This was Feldman's only mention.
At the beginning of season 2, episode 3, the name DiLucca pops up again in season 4, episode 16 and season 7, episode 17. That season 4 character is a civilian, not a detective. There is no other DiLucca character showing up at any other time in the series.