As I understand it, when Sears died so did the warranties on tools purchased from them. Stanley Black and Decker essentially bought the Craftsman brand name and manufacturers the current tools. They are under no obligation to honor the warranties on older tools bought from Sears. The serial/part numbers are used to differentiate the old from the new. In general, the older the Craftsman tool is, the better it's quality is as well. I have wrench sets, sockets, ratchets, pliers and many screwdrivers I got in the 70's and early 80's that are still going strong. Some Lowes and Ace hardware stores are said to honor warranties on some tools, usually simply ones like screwdrivers etc., if they have the exact same item.