Vintage Snowmobile yard find 

I remember being told... years ago, one was a 1967 and one a 1968 (I have two). I do think he had a 1969 also. I can't figure it out myself. One clue I used was the registration. It was good for 3 years back then. So working backwards from 71-74 (what is on the hood), would it be 67-70? or 68-71? 69 doesn't seem to fit using the registration math. I have the registration card from it, from 1974? as it says it expires in Feb 1977. Model P17H (17 HP Hirth). Its a bit of a mystery to me. I'm going to take a look the reg sticker on the hood again. Maybe I can see the one underneath. But maybe there is something obvious about the sled itself that dates it. I'm guessing that's what you used. Thanks for watching and the comment! Let me know what makes it a 69.