Table schema:
CREATE TABLE table_name_75 (competition VARCHAR, venue VARCHAR, notes VARCHAR, year VARCHAR)

Question: Prior to 2004, what was the name of the competition that took place in Johannesburg, South Africa and had the 400 m hurdles event?
SQL: SELECT competition FROM table_name_75 WHERE notes = "400 m hurdles" AND year < 2004 AND venue = "johannesburg, south africa"