If you have an Ariens lawn/garden tractor built after 2009, the age of your tractor can be found in the serial number. The first 6 digits of the serial number before the letter are the month, day, and year of manufacture.
This applies to model numbers starting with 936, such as: 936001, 936007, 936037 through 936101
Serial number example: 010413A000111
01 - Month
04 - Day
13 - Year