CREATE TABLE table_68664 ("Year" FLOAT, "Team" TEXT, "Co-Drivers" TEXT, "Class" TEXT, "Laps" FLOAT, "Pos." TEXT, "Class Pos." TEXT)

Name the class for 4th position with year before 2006
SELECT "Class" FROM table_68664 WHERE "Pos." = '4th' AND "Year" < '2006'
SELECT "Class" FROM "table_68664" WHERE "Pos." = '4th' AND "Year" < '2006'