Standbys for a sold-out flight aren't cleared until about 10-15 minutes before departure. Actually I just checked and there is 1 seat for sale on 2840 in either Y or B class. All other fare classes show 0 available so still no SDC possibility. The flight may even be slightly overbooked. Remember if you get on the standby list and clear you will be charged for SDC anyway. Good luck.

ETA: And, edleo13, welcome to Flyertalk!