An axial lead connector assembly for an implantable medical device (IMD) facilitates electrical connection between an implantable medical lead and circuitry contained within the housing of an IMD. A connector header defines an axial stack bore to receive an axial stack of in-line connector components. The connector components define a common lead bore to receive a proximal end of an implantable lead. The in-line stack of connector components may include seals, electrical connector elements, a strain relief, and a locking device, each of which defines a passage that forms part of the lead bore.