I have a model 7266 and was lucky to get two original owner's manuals with it. They are copyrighted 1976 and 1977, implying that the mower can't be older than 1977 -- but I'm guessing that it was built in the early 1980s.
I'm always on the lookout for another Lawn Boy (two-stroke, not self-propelled) and sometimes I come across somebody who seems to think that these old mowers are valuable to collectors. I'm skeptical about that. They are great mowers -- better than anything made today.
Here's a picture of my 7266.
Does yours look similar?