CREATE TABLE table_37439 ("Race" TEXT, "Length" TEXT, "Class" TEXT, "Circuit" TEXT, "Date" TEXT)

What is the length of the 6 Hours of Talladega?
SELECT "Length" FROM table_37439 WHERE "Race" = '6 hours of talladega'
SELECT "Length" FROM "table_37439" WHERE "Race" = '6 hours of talladega'