The engine date on this Roper ride on mower is 1984 but it may not be the original motor thus making the id of the year of build a little more difficult ,once you know the cutting deck size and wheel sizes and other specifications it helps to narrow the field down.
Dembones your mower can't be the 7 speed version,I have a pic of that below it's a different gearbox, your mower is classified as an eight speed gearbox (2 reverse, 2 first ,2 second , 2 third gears)
Here is a brochure ,copy and paste the following web address https://www.google.com/url?sa=i&url=http%3A%2F%2Fwww.searstractormanuals.com%2Ftest%2Fetc%2Froper_1979.pdf&psig=AOvVaw3_JQYAs8_QFwcI5F1b1s8s&ust=1581825738950000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCJjrjZ7W0ucCFQAAAAAdAAAAABAD
