GM Service Manual Online
For 1990-2009 cars only
Figure 1:

Hands-Free Microphone


Object Number: 397514  Size: MF
(1)Hands-Free Microphone
(2)Dome Lamp Harness
(3)Overhead Console
Figure 2:

Sensing and Diagnostic Module Connection


Object Number: 357186  Size: MF
(1)Shifter Assembly
(2)Sensing and Diagnostic Module (SDM)
(3)Floor Handset Connector
Figure 3:

Onstar Components - RR of vehicle


Object Number: 875592  Size: LF
(1)OnStar Cellular Antenna
(2)OnStar Cellular Antenna connector
(3)Body Harness
(4)C474
(5)Vehicle Communications Unit (VCU)
(6)Vehicle Interface Unit (VIU)