I have a 96 deville with stock radio/cassette. Trying to install after-market radio with a Scosche GM-03B harness. I have power and sound from only one speaker (LF.) After viewing all pages in this forum, and many others, and the diagrams by the professionals in this forum and all suggested links, I compared the 32 pin-outs with the car harness and see slight differences such as Pin E15 should be RF+ but it is actually a stranded wire in a thick clear plastic coating that I would venture to guess may be a Negative feed. Oddly enough, there are only 3 such wires, in Pin E14, E15, and F14. I would have expected one for each floating negative. Any ideas?!?!

Sounds like you have the delco active audio system it has an amp in the trunk on the back of the back seat the dash has only the head unit . sts96