Manufacturing date has different meanings. Does it mean the date the complete product was placed in the box and was sent to the finished product warehouse, when the component parts were made, or some period in-between? Manufacturers at one time accumulated stockpiles of component parts, and they also could have remained in inventory for prolonged periods when sales get slow. That's not so common now, as most companies know that raw materials, parts, and final product inventories held beyond current sales needs represent idle capital, so modern business practices dictate that inventory levels must be controlled very tightly. That wasn't always the case.