On what date was the number of locomotives 421-6?
CREATE TABLE table_name_70 (date VARCHAR, loco_nos VARCHAR)
SELECT date FROM table_name_70 WHERE loco_nos = "421-6"
### Context: CREATE TABLE table_name_70 (date VARCHAR, loco_nos VARCHAR) ### Question: On what date was the number of locomotives 421-6? ### Answer: SELECT date FROM table_name_70 WHERE loco_nos = "421-6"