Typical hull identification number (HIN) consists of 12 letters and numbers. The first 3 are the US Coast Guard assigned manufacturer identification code (MIC), the next 5 is the serial number assigned by the manufacturer, the next letter represents the month construction , i.e., A = Jan, etc. started, the next number is the year of certification and the last digit of the year it was built and the last two number indicates the boat's model year.
My 2004 Hunter 386 had a construction start letter of "I" for September, "3" for certification and construction year and "04" at the end for model year.