N7733B is taken. It's currently assigned to a 2006 Boeing 737-76N registered in Wood Dale, IL.
See the full aircraft record →A tail number only frees up if the owner deregisters the aircraft or moves it to a different N-number — and even then the FAA holds it before releasing it to the public.
N7733B has been worn before. Past registrations from FAA deregistration records:
Tails one nudge away from N7733B that aren't assigned or reserved: