I was vacationing in the Ogden area of Northern Utah and found a guy with a few truckloads of Mustang parts for sale. There are no K code unique parts that I saw, but he has a multitude of 65-66 parts and some 67-68. He had a lot of sheet metal, glass, a few rear ends and instrument bezels, and host of other things buried in boxes. He seems to be a pretty straight guy, but does not know Mustangs as he is into Mopars. I picked up a couple of things and the prices were reasonable, and he seems to be motivated to move things. His name is Cris and he can be reached at 801 726-3159. For those in the area, he is in Layton which is between Ogden and Salt Lake.
Jay
PS he had no fast back interior trim pieces that I could find, but did have 2/3rds of a fold down seat. He also had one set of extractors (outside and sliding vents)but without the inside fiberglass/grill pieces.