An implantable medical device (IMD) includes a housing that is formed of a biocompatible material such as silicone. The housing includes integral contact receptacles that house individual contacts, which contacts are electrically connected to electrical circuitry within a main interior cavity of the housing. The integral contact receptacles receive electrode leads, and the contacts are aligned with electrode terminals on the proximal end of the electrode leads, which establishes an electrical connection between the electrical circuitry and electrodes at the distal end of the leads. The housing is filled with a silicone gel such as a tacky diphenyl silicone gel. The silicone gel provides electrical, mechanical, and thermal insulation, and prevents the ingress of bodily fluids when the IMD is implanted.