I had my MB Tex seat covers and carpeting replaced last year by a very reputable and expensive restoration shop - Paterek Brothers in Chatham NJ. The seat covers and carpet set came from GAT.
They did the seats first and everyone agreed that the old smooth, but deteriorating tex material was original to the car. After removing the seat covers they found the original seat pads were in decent condition and not rotted, just soft in areas especially the drivers seat. The advise I got from Paterek was to firm and stiffen up the pads with foam in certain areas and re-create those nice firm corners. They could make the seats as firm as I wanted. I took their advise and am very happy with their work and the way it turned out.
BTW, they told me that the original pads are not horsehair, but are in fact coconut husks with some sort of glue to bind, mold and shape the pads.
Has anyone heard of this ?
jz