CREATE TABLE table_26464364_1 (us_viewers__million_ VARCHAR2, production_code VARCHAR2)

How many million U.S. viewers watched the episode with the production code 3x6004?
SELECT us_viewers__million_ FROM table_26464364_1 WHERE production_code = "3X6004"
SELECT "us_viewers__million_" FROM "table_26464364_1" WHERE "3X6004" = "production_code"