CREATE TABLE table_23652 ("LMS 1932/3 No." FLOAT, "LMS 1946 No." FLOAT, "BR No." FLOAT, "Date built" TEXT, "Date motor gear fitted" TEXT, "Withdrawn" TEXT)

When was the motor gear of the LMS 1946 no. 1901 model fitted?
SELECT "Date motor gear fitted" FROM table_23652 WHERE "LMS 1946 No." = '1901'
SELECT "Date motor gear fitted" FROM "table_23652" WHERE "LMS 1946 No." = '1901'