I have a 1998 Astro with conversion and 4 speakers in front and 4 speakers in back. The original radio connector was lost during a recent dash operation. I have new connectors but do not have a good wiring diagram that shows all the pin positions for 16 wires in the harness. The unit has 4 pairs of speaker wires, 2 power, one ground, 2 dimmer, one power antenna wire, and three left over. I think at least 2 go to the rear sub-amp system and the 4 rear speakers and one wire goes to the Speed volume control. I need to know where exactly they go in the connector of the Delco radio #16265885

You mention 16 wires in your harness. See if this 20-pin unit can help with your needs.

Click Here

Thanks for the information. I still don't see the extra wires used on this model. It must have some out control from the radio to turn on the rear amplifier as well as a wire input for the speed controlled volume. I will persevere to find the answers and then anyone else who may need it will have it.

I believe that link I posed contains some other links to sources of harnesses and adapters. Perhaps running those down will provide your answers, or at least put you in contact with a place which could supply a custom harness.