NPC #28783 (possibly named "Riding Gryphon Amored Neutral Taxi") doesn't exist. It may have been removed from the game.
Did You Mean...
Riding Gryphon, Amored, Neutral (Taxi) - Live
Riding Gryphon, Amored, Neutral (Taxi) - PTR
Riding Gryphon, Amored, Neutral (Taxi) - PTR 2
Riding Gryphon, Amored, Neutral (Taxi) - Wrath of the Lich King
Riding Gryphon, Amored, Neutral (Taxi) - Cataclysm