An implantable lead extension includes an intermediate body element； a plurality of proximal tails attached to a proximal end portion of the intermediate body element； a plurality of terminals disposed along each of the plurality of proximal tails； and a connector assembly attached to a distal end portion of the intermediate body element. The connector assembly includes a plurality of connectors； each configured and arranged for electrically coupling with a different stimulation lead. Each connector has a connector housing defining a port for receiving a proximal end portion of a stimulation lead, and a plurality of connector contacts disposed in the connector housing. The connector contacts can couple to terminals of the stimulation lead when the proximal end portion of the stimulation lead is received by the port. Conductors extend along the longitudinal length of the intermediate body element and electrically couple the connector contacts to the terminals.
