If you don't already have a Chrysler factory service manual, you can free-download one at
www.mymopar.com. It has a very nice electrical schematic section, which includes radio wiring.
What model year of vehicle? If you are talking about the Fuselage years, there were NO 4-speaker radios, just 3 (right, left, center) across the front, to which two additional speakers could be added (with a dual-gang f/r fader mechanism) to the rear. Normally, C-bodies came with the 5-speaker system.
On these stereo/multiplex radios, there were three power wires coming out the back. They then went to a Clectron box which made the right, left, and center channels for the front speakers.
THREE front speakers? Yes. The Clectron box merged the right and left channels for a blended center channel. This gave a continuous stereo effect across the front windshield of the vehicle, rather than right or left being at the ends or in the kick panels. For the 1974+ C-bodies, this arrangement vanished, to return on the Chrysler LH cars and their improved sound systems (number of speakers and higher-power factory amps).
Chrysler used "ungrounded" speakers. These speakers had a + and - terminal. Which matched the radio's amp outputs, usually. For the 1979 R-body cars (maybe others, too), front speakers were two-terminal, but the factory rear speakers were "self-grounded" speakers, with only a power wire, using the speaker's metal housing for an "internal ground circuit". When replacing a factory speaker, you'll need to run a wire from the - terminal of the speaker to one of the speaker attaching screws to complete the ground circuit.
ONCE you understand how they all were wired back then, easier to deal with things of that nature.
What I mention above relates to my discoveries and adventure in upgrading the AM w/rear speaker factory radio in my '70 Monaco Brougham to a factory AM/FM Multiplex radio will all 5 factory speakers, in about 1975. At the time, ALL of the needed items were available from Chrysler's northern parts warehouse except for the front to back speaker harness (which I made myself). The front r and l speakers, I hung off the lower edges of the instrument panel structure (not wanting to get into the deal of getting a different instrument panel pad and related speaker mounting brackets). So, I got the front factory harnesses, rear dual-gang fader, radio, and Clectron box.
Some might claim the Clectron box is not needed, which might work for them, but I wanted the full factory situation. BTAIM
Enjoy!
CBODY67
