Originally Posted by
3Cforme
Welcome to FlyerTalk.
One can use the
Advanced Routing Codes feature of ITA Matrix to look for dates and flights with T availability specifically. If you can book online, search for found flights on delta.com; if booking by phone, ask the agents for date/flights.
http://matrix.itasoftware.com/
In the Advanced Routing Code fields, dl+ means one or more DL-coded flights. bc=t means T booking class.

AH! Thank you for that! I'd read it was possible to select specific fare codes on Matrix but didn't know how it was done (and, admittedly, didn't google how to do it but the help icon for advanced routing codes doesn't mention that)