I'm confused too!
What you describe sounds like the lines to raise/lower the CB, but that was not used until the 1971 and later models (well, Rudy changed back to the lever-operated CB on the boats that he built in the 1990's), the 1969 had a lever-operated CB and I'm not sure what those lines and blocks are that you describe. Perhaps the reason that your boat is in such good shape for a 1969 is that she is really a 1971 or newer? If 1973 or newer (some 1972 models as weel) there will be a 12-digit HIN on the outside of the transom, the last 2 numbers in that HIN will be the last 2 digits of the model year.
Earlier boats had a 2-part "serial number", there would be a Hull# and a Class#. Hull# showed how many total O'Day sailboats had been built (my 1969 Widgeon was H# 22698) and Class# was the number of that class (in the case of a widgeon, how many widgeons, mine was #1791).
Does your boat have a foredeck? or is there just a flotation tank that is about 12" +/- below the gunwale? Are the side seats molded in or are they wooden? 1971-82 has a foredeck and the cockpit seats are molded as part of the deck, 1984-present is open bow to stern with molded-in seats along the sides with a seat-level platform forward of the mast. 1963-70 models have wooden seats, a flotation tank in the bow, a flotation tank (seat-level) across the stern and a molded "seat" across the boat that the mast steps thru.
I'll include a diagram of the later model CB control lines below anyway.