A connector for an implantable medical device includes a lumen extending from a port defined along a length of a connector housing. Axially-spaced-apart connector couplers are disposed along the lumen and are configured to couple to a proximal end of an inserted lead or lead extension. Each of the connector couplers includes a plurality of circumferentially-spaced-apart coupling members and at least one elastic member. The plurality of circumferentially-spaced-apart coupling members each have inner surfaces and outer surfaces. The inner surfaces of the coupling members are configured and arranged to couple to the proximal end of the lead or lead extension when the proximal end of the lead or lead extension is inserted into the lumen. The at least one elastic member couples the coupling members to one another such that a distance between the coupling members is expandable.