I bought them used from Michel who was parting out a coupe a few months back in Switzerland. He wanted to sell the seats, but that was not practical to ship them, so he agreed to remove the covers and send them (Michel, thanks if you are reading this). The whole rear seat horsehair comes off the shell in one piece as you see in the pictures. It was dry, but still in pretty firm condition and I just used extra 1/2" high-density foam to pad it up a bit. I had some thinner foam too, to fill in the gaps that had more crumbling horsehair, as needed, but behind the 1/2" foam, so I don't get a line showing. Then put the cover on horsehair, sew the edges, tighten it from back of the horsehair and put them into the shell and glue the sides of the vinyl to the shell. That's all. Really easy, but messy (from the crumbling horsehair), and lots of needle cuts on the fingers. I guess the horsehair can be replaced with a solid foam, but need to do a lot of carving to get the right shape, especially in the back. But, now doing this, I wonder if the 635 horsehair can be made to fit into the 3.0 shells!! 635 shells, has just a little different shell that doesn't fit into the coupe, but I am sure the pad can be manipulated to fit. And, there are lots of them around that could have good pads in them, or even new ones may still be available for them. Now I have to go to the junkyard and see one of those seats! Anyone done this?