Chris : I checked my '66 Color & Upholstery Book ; not much help. It only has one actual carpet sample, but does list the other colors available. The good thing is that it only shows one blue for Mustangs ; a Medium Blue. The other Blue, a Dark Blue notes only for Thunderbirds. I have attached copies of the sheets that pertain to Mustangs. Since the carpet sample is rather thick, I couldn't get a good scan of the text, so I took a picture of it that I have also attached.
The next thing I decided to do was to check my "1966 Only Parts & Accessories Catalog" to see if, by chance, the '66 used the same carpet Part Number as the 65's. Sure enough, the same C5ZZ Part Number for the Front Carpet, and suffix of AAD.
Then, "I made the mistake" of checking my "1965 Only Parts & Accessories Catalog. It shows the same Part Number for the Front Carpet, but shows a suffix of "DAD" before 8/17/64, and "UFC", after 8/17/64. Now I've added more confusion to the pot.
It seems like the real key here is correlating the suffix codes to a color or swatch. Now, where to find that ??
I tried.
Bob