After so many years these have started to perish for many owners, especially on cars that have been driven as the engine/exhaust fumes I believe shorten it's life.
For some time we have believed that they are the bump stops found inside suspension struts and actually the RS200 suspension seems to use them although I have never taken one apart to be sure.
Thanks to other owners suggestions (especially JBH) I found a pair on Ebay advertised as "Cosworth Genuine Bilstein Bump Stops".
Having bought 2 I finally plucked up the courage to take my old ones off and you can see the are identical and even have the same part number VS-3972 on them with the RS200 one's having been sawn down just under that number.
I cut the two down and sprayed them black and they fit a treat.
If you click on the images they rotate round the way
