There is very little in reliable documentation. I have found many omissions and errors in the service manual diagrams.
Also, I have never found the exact diagram of the base models, only Limited and SRT. Of course, the base cars have no amp and the speakers are wired directly to the head.

In my (Base) SE, I found that I didn't need a diagram, as I put in a new head and added my own rear speakers - doing it all myself makes it simple.

THIS is a good thread for understanding the sound system wiring, in particular, the amp:
https://www.crossfireforum.org/forum...-channels.html

The service manual diagrams seem usable to me. I have a hard copy of the "Wiring" chapter of the service manual and so far, I've been able to follow it for any of my work.
You can find the entire service manual here:
https://www.crossfireforum.org/forum...ollection.html