Originally Posted by azstar

The inventory letter could be the same for Classic Plus, Classic, and Economy, so that won't help. Try searching for a fare "without restrictions", or "without penalty" or "refundable" if you have those options. If the fare basis (the lengthy code printed on your ticket) ends in "5" it's economy. If it ends in "3" it's classic, and if it ends in "1" its classic plus. That's how they differentiate when ticket is issued and at check-in.