CREATE TABLE table_68987 ("Class" TEXT, "Type" TEXT, "Fleet numbers" TEXT, "Quantity made" FLOAT, "Manufacturer" TEXT, "Date made" TEXT, "Date withdrawn" TEXT)

What is listed as the Date made with a Quantity made of 13?
SELECT "Date made" FROM table_68987 WHERE "Quantity made" = '13'
SELECT "Date made" FROM "table_68987" WHERE "Quantity made" = '13'