Alchemist Gribble is located in Honor Hold in Hellfire Penninsula.
Face toward the Honor Hold keep and look at the tower to the right, on the hill. You will find him inside the tower on the bottom floor, standing on a table. (53.8, 65.8)
TomTom command
/way Hellfire Peninsula 53.8 65.8 Alchemist Gribble