An implantable lead connector assembly includes core and contact circuits held together and isolated from one another by insulation. The core circuit includes a conductive core and a conductor pin, which has a proximal end coupled to an outer surface of the core, and a distal end spaced outward from the outer surface and protruding distally from the insulation. Insulation sealing surfaces extend on either side of an outer contact surface of each contact circuit, and the sealing and contact surfaces define a uniform outer diameter of the assembly. A conductor pin of each contact circuit has a proximal end coupled to an inner surface of a contact ring of the corresponding circuit, and a distal end that protrudes distally from the insulation. The insulation may be formed by injection molding, and then outer surfaces of the molded insulation and contact ring(s) are ground down to the uniform outer diameter.
