I finally got the headrests in PA, and the rails in Germany. They are now fitted, and look well, although I did make a bit of a mess with the first hole in the Tex, where the grommet fits in.
For anyone doing this job, the metalwork is easy, although I did have to cut off the drilled lugs on the bottom end of the slides, and re-drill a couple of inches further up, as the lugs were coming exactly under the small drilled metal plates which receive the self tapping screws which hold the seat backs on. To prevent distortion of the slide, when the nut and bolt is tightened, due to it's shape, it is necessary to fit a little plywood packing piece.
I found that the most difficult part of the whole operation, was cutting out the seat padding to receive the upper end of the slides. Difficult, because one has to be fairly accurate, particularly near the very top, so that the grommets are a tight fit, it is almost impossible to see what one is doing, and the material itself, which is like rubberised hemp, is difficult to work with.
Tom Koellner gave me a lot of good advice, such as work from the bottom up, and do not cut the Tex until almost last, or you will end up with too large a hole in the seat cover. He also suggested making the holes with a drill. The drill does not actually bore a hole, but the stuff wraps itself around the bit, and can be pulled out. I found that I was unable to control my (rather fast) drill, and it was inclined to tear out huge chunks, so I bought a box of surgeons scalpels, which did the job.
Also, I gave up on trying to cut, blind, in the upholstery, an accurate shape to receive the push on from underneath plastic washers which retain the grommets in position. The grommets and retainers are oval in shape, and as my seats are earlier thin ones, there is very little space for them, due to the stiffening of the upholstery at front and back of the seat. Therefore I used a good dollop of Copydex, which is a fabric adhesive, when finally fitting the grommets in. It all seems quite solid and neat
Finally, I would like to thank all the forum contributers, who pointed me towards Tom, in Germany, and also Douglas Kim, with whom I have been in direct contact, and who gave me a lot of help. I just hope that these notes will help someone else
HAC (IRELAND)