Thought I'd resurrect this topic with a few recent photos that I took of my original 1967 Convertible underlayment, and the Ssnake-Oyl replacements...
I'm not sure if I've got all of the little broken pieces exactly in the right spots, but the first image is the original asphalt underlayment and the padding that went between the underlayment and the carpet - or perhaps this padding was originally attached to the carpet (more about this below). Unfortunately, the original black carpet was very moldy and I had to throw it out many years ago, so I can't check it...
The second image is the Ssnake-Oyl replacement underlayment pieces next to the original padding. I do like the Ssnake-Oyl pieces, but for some reason, they put the fabric backing material on the wrong side...
The third and fourth images show the original backing material on the underlayment - sort of a jute fabric under all of the pieces except for the transmission tunnel piece, which is more of a plastic wrap material...
The fifth image is the backing on the Ssnake-Oyl pieces - a plastic similar to the backing on the original transmission tunnel underlayment...
The sixth and final image is a label I found on the underside of the rear floor padding. It looks like it says "RUG" on the top line, then "C6ZB-76 I ..." on the next line, and then "V BLACK" on the final line. It's because of the word "BLACK" that I'm wondering if this padding was originally glued to the underside of the black carpet, as there would be no reason to label just the padding itself as being BLACK...