Look at the code posted
All Oday boats built after November 1, 1972 (and maybe a few built before?) will have a 12-digit HIN. I don't want to repeat the whole thing that "Widgeon" posted but will hit the important points.The basic format was: XDYmccccMyyA (1973-83 model years, 1984 and later was slightly different)XDY = O'DAY (boats built during the mid 1980's may have STR)m = Model code (J = 22)cccc = Class # (how many boats of that class had been built: example, if this number were 0345, this would be the 345th boat of that class built)M = indicates Model Year Format is usedyy = Model year (so M79 would be 1979 model year)A = Code for month of production. Model year was August to July, 1975 model year for instance would be Aug 1974 to July 1975. A= August, B= Sept. etcIf DaveH's boat has a HIN ending in M75I (the last digit is "I" not 1) then this would be a 1975 model, built in April 1975The complete HIN would look like: XDYJccccM75I (fill in the correct number instead of the "cccc".