I recently bought a Chevy radio #986847 AM/FM and a converter/adapter that mounts under the dash. The adapter has 4 knobs,Volume,Tone,Balance and Rear/Front speaker. This adapter has a 12 pin plug and one other wire that goes into a slide type plug and a black wire coming out. Where do these plug into?? I have read where these are rather rare with only a few hundred made?? I do believe both of these pieces are Chevrolet. Any and all input is greatly appreciated.

Remove the plug on the side of the radio and it will reveal the multi-pin receptical the second unit plugs into.

If you can't figure it out I could send you a diagram/picture.