Tiller dating

I'm trying figure out how old my tiller is. I have a pic of the original Briggs engine cover with the numbers stamped into it. I learned that anything from 65 and up that the last group of numbers has the date in it. Year month day two digits each then two more for plant and assembly line info. My last group of numbers only has 7 digits so does that mean it is older than 65 and if so how do you decipher the number. Any help would be great.