Floor Drain Plug Sealer Mats?

[85 Cutlass Brougham]

Well, I am finally putting my Cutlass back together now. One of the things I will need to do soon is put the drain plugs back in the rear passenger foot wells, but I have no idea where to find the rectangular pieces of adhesive tar mats used by GM when it was new. They covered the plugs completely. Does anyone know where I can buy them?

 

[supercrackerbox]

No idea actually, but when I re-did the interior of my Charger, I just used some pieces of cheap knock-off Dynamat from Ebay. Should function just as well, and would be hidden from sight regardless.