CREATE TABLE table_10555 ("Class" TEXT, "Wheel arrangement" TEXT, "Manufacturer" TEXT, "Year made" TEXT, "Quantity made" TEXT, "Quantity preserved" TEXT, "Year ( s )  withdrawn" TEXT, "Comments" TEXT)

How many have a class of 330?
SELECT "Quantity made" FROM table_10555 WHERE "Class" = '330'
SELECT "Quantity made" FROM "table_10555" WHERE "Class" = '330'