WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Inside Rear View Mirror
Courtesy of GENERAL MOTORS CORP.
Fig 2: Vehicle Communication Integration Module (VCIM) C1
Courtesy of GENERAL MOTORS CORP.
Fig 3: Vehicle Communication Integration Module (VCIM) C2