I updated this thread today for the 7th gen models.

Fun fact, this is the first time that I have run across Subaru re-using a chassis code.

It would need a few years to have a legit overlap, but a theoretical 2000 Turbo Sportshift Baja (I know that didnt exist in 2000, but work with me here) would have a code of BT9AYET, which would also be a 2020 Outback 2.5 i-Touring. I wonder if they will change something in the model codes before the 2022MY when there could be actual overlap of models..