I'm guessing that is a mid 70's model. Probably a 75 or 76. I had one just like it but a 21 inch cut. It was a 1976 model. I'm also guessing you could maybe get $100.00 for it if it is in good shape and runs good, to a lawn boy enthusiast. Toro or Lawn Boy has a web page that lists all the models by year that I used to look at from time to time. But when I got a new Mac computer
awhile back I can't find it anymore. I think it was pages from an old manual. Hope this helps.
Regards,
Jerry