UA 447 then DL 3876 at Denver
Tulsa → Denver → Austin
Timetable, Denver time
10:06UA 447 from Tulsa at the gate
09:42DL 3876 to Austin leaves the gate
23 h 36 apart on the timetable, overnight
DL 3876 leaves 23 h 36 after UA 447 arrives on the timetable: more than half a day, so not a connection we count.