i think it was '72 when HID numbers became mandated by the USCG....double check the transom about at the water line...passanger side.
also, is there an ID plate in it? the piece of metal plate that says the HP and weight rating for the boat. Sometimes the MFG's stamped the numbers on there. is there a registration sticker on the boat? if so, what year is it?
when I registered my '71 wriedt, it had been so long since it was last registered ('83 i think) that it fell out of the DMV system so it was like registering it for the first time. I did not have a title for either the trailer or the boat. All I had was old registration from '75. The boat didnt have a HID stamped in the hull, but it had numbers stamped into the ID plate (top left side). The numbers were specific to the boat (7109 - year 71, 9th boat) and she wanted to give me a new HID number for the title because that number was already used for another boat in the system. I batted my eyelashes at this cougar and I was able to keep the number. I was able to walk out of there with a temporary title on the boat, but I had to come back to get a VIN put on the trailer because I couldnt find one anywhere on there and the plate that was on the trailer was from a car.

I will probably be going through your same pains here shortly with the trailer thats under my liberty. The title is screwed up and the guy i bought it from gave it back to the guy he bought it from who is trying to get the guy that he bought it from sign it in the right spot.

I think its a lost cause and i will just hit up the DMV with a bill of sale and the license plate and see where i can go from there.