68 Camaro Radio Wiring

[dtep]

I'm rewiring a 68 Camaro RS with an American Autowire Update harness.  The car had a Motorola C068A AM radio that wasn't hooked up when I bought it and I'm struggling to figure out what the wires coming out of the radio are for.  The radio has writing on the side and a sticker on the bottom which makes me think that it came from a junkyard or something though I did find this model identified online as being original for the 68 Camaro.  The connector for the wires looks like a connector for a trailer's brake lights but is molded to the wires so it doesn't appear that someone kluged it on there.  There is also another wire on the other side that has a woven jacket on it and a spade connector.  I'm guessing that this is a chassis ground but am open to other ideas.  Can anyone help me out here?  Thank you!

[boomer632]

GM did not install that radio. More than likely installed by a dealer as a retrofit. You are correct that is a trailer plug. The wire strap held in with sheet metal screw is another shade tree mod.

[KurtS]

Common dealer-installed radio. Should be a simple diagram somewhere to confirm the wires. But should be +/- and speaker +/-.
You'll need to convert those connections to the harness connector.

[GMAD_Van Nuys]

I found a Motorola service manual on eBay for 1968 model radios:

https://www.ebay.com/itm/335707772046?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20220405142716%26meid%3Db945db6462d3402aa180c0f2fead2158%26pid%3D101506%26rk%3D3%26rkt%3D10%26sd%3D335620855876%26itm%3D335707772046%26pmt%3D1%26noa%3D1%26pg%3D4481478%26algv%3DDefaultOrganicWebWithV11WebTrimmedV3VisualRankerWithKnnV3AndUltBRecall&_trksid=p4481478.c101506.m1851

[dtep]

Followup - I did a search online for C'upper case O'68A instead of C'zero'68A and got a hit for a service manual on eBay for this exact model.  I bought it and found that the trailer connector is also a factory-installed Motorola radio connector!  Starting from the male end, the first two conductors are for the front speaker which has a compatible two conductor version of the "trailer" connector.  The other two conductors in the radio connector are for rear speakers which must be controlled by a rear speaker controller KM15S or KM19S.  I don't have one of these controllers but am assuming that it plugs into those conductors and then has outputs for rear speakers.

The wire with the woven jacket on the other side of the radio is the power lead.  The lack of a ground connection makes me think that the case is the ground.

While I realize you don't have the service manual in front of you like I do, I'm open to other interpretations from more experienced people.  Thanks for your inputs above.