CREATE TABLE table_20589 ("Institution" TEXT, "Location" TEXT, "Founded" FLOAT, "Type" TEXT, "Enrollment" FLOAT, "Nickname" TEXT, "Joined" TEXT, "Left" TEXT, "Current Conference" TEXT)

Name the current conference for 1974, 1989
SELECT "Current Conference" FROM table_20589 WHERE "Left" = '1974, 1989'
SELECT "Current Conference" FROM "table_20589" WHERE "Left" = '1974, 1989'