N143 is taken. It's currently assigned to a 2023 Gulfstream Aerospace Corp GVI (G650ER) registered in North Salt Lake, UT.
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.
N143 has been worn before. Past registrations from FAA deregistration records: