Hi,
I found that a radio wiring harness adapter from Crutchfield works with my stock harness that was connected to a Reno stereo. I was about ready to start cutting when I found this and decided to order it to see if it would work. Crutchfield does not currently include it if you are buying a stereo for an '87 so I'll see if I can get them to update their technical info.
The part number is 120701822. Crutchfield refunded the purchase price of the adapter since it could have been included when I bought the stereo earlier (they only included speaker harness adapters when I bought the stereo).
Hope this helps someone!
Eric
'87 930