The BDC 16 body is dated 3-72. It is a stock alky/gas carb for a 101 series can can be use on other McCulloch's. The BDC 22 body is 5-73. The inlet needle is a larger style and the main tube in the venturi is enlarged with the larger alky hi speed needle. These are nice clean carbs, the throttle shafts fit snugly.