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

Radio Wiring


Object Number: 331838  Size: MF
(1)IP Harness
(2)Radio Connector, C2
(3)Radio Connector, C1
(4)Radio Connector, C3
Figure 2:

Rear Speakers


Object Number: 311431  Size: MF
(1)Rear Speaker Connector, RR
(2)Rear Speaker, RR
(3)Front to Rear Body Harness
(4)Rear Speaker, LR
(5)Rear Speaker Connector, LR
Figure 3:

Radio Speaker Jumper Harness


Object Number: 277996  Size: MF
(1)Radio
(2)Speaker Harness
(3)Turn/Hazard Flasher Wiring
Figure 4:

Rear Speakers (Regular Cab)


Object Number: 277993  Size: MF
(1)Left and Right Rear Speakers
(1)Left and Right Rear Speakers