HIN
The Hull Identification Number (HIN)is likely outside centre transom, halfway up, or inside cuddy, starboard bulkhead.It should read something like mine XDYD77840974where the XDYD indicates daysailer made by o-day. The next four number are the hull and sail numbers 7784 being the 7,784 hull made by o-day from that mold, and the last four vary by manufacturer, but indicate the date of manufacture, mine being 09 (September) 74, (1974). (Some manufacturers had letter codes i some years)According to my records, the Daysailer III was only manufactured between 1987 and 1992.As for the spreader arm, you can fabricate one yourself from 1/2 x 24" aluminum tubing or rod, a drill, hacksaw and file. They can also be ordered from D&R marine. http://boonedocks.net/daysailer/drmarine.htmlThe spreader bar is $9.50