UA 5463 then DL 3876 at Denver
Billings → Denver → Austin
Timetable, Denver time
12:21UA 5463 from Billings at the gate
09:42DL 3876 to Austin leaves the gate
21 h 21 apart on the timetable, overnight
DL 3876 leaves 21 h 21 after UA 5463 arrives on the timetable: more than half a day, so not a connection we count.