I checked the invoice for K3 s/n 2295, my older K3. It has the KXV3. As I am purchasing the K144XV, I have added the KXV3A upgrade to my order. Since I have an OCXO, I am also ordering the K144RFLK. Thanks to Gary of Elecraft (and several others) who responded. Elecraft support, both from home base and the user community, is first class and rapid. Jim/N1NK