I think Randy and others are correct on what will work on some A/S and not others. It did work on my '83 Sovereign
however, and just for information, here's how I did it:
I used a spray bottle with straight amonia and sprayed about a one to two foot square area. Let it sit for as long as it takes to put the spray bottle down and pick up two sheets of paper towels and start wiping the amonia off, starting at the seams. The amonia liquified the clearcoat and it rubbed right off.