Amadeus has the same codes for TG as KVS etc. if you use real amadeus, not these web interfaces.
777 = 777-200ER
772 = 777-200
773 = 777-300
Problem is TG's stupid new booking engine translates them to longer descriptions found in Amadeus, so
777 = 777-200ER (Boeing 777-200/300)
772 = 777-200 (Boeing 777-200/200ER)
773 = 777-300 (Boeing 777-300)