O'Hara is indeed Universal. Reruns aired in the early 90s on A+E as part of a package deal of other short-lived Universal shows that also included "Ellery Queen", "Delvecchio", "City Of Angels" and "Mrs. Columbo" (which should stay buried even though two episodes got stuck as "bonuses" on the regular "Columbo" releases).
RTV showed several episodes of O'Hara a few years ago. As a David Janssen fan, I found them hard to watch. From what I've read, Janssen hated the show. Fortunately, a few years later we got Harry O, which is one of my all-time favorites. I'm very thankful Warners released the entire series, although I wish they had remastered it.