Bumping this. The last piece I need to complete my interior restoration. Attaches to the rear-most edge of the rear quarter trim panel. It's a small stainless piece with one screw attaching it. I only need the passenger side but will buy both if you have them. I've seen them on Old's and Pontiac convertibles as well. Should be the same for 63 and 64.
Have you contacted willigton Cadillac? He has a 63 convert parts car.