Hi, this part is probably still available from your local OPC, however there are lots of Porsche breakers who should be able to source you a good SH one. Removing it is the easy part, the old one can simply be carefully extracted from the rubber. Fitting the new one will be more awkward. I found it easier to actually remove the window entirely, remove the rubber from the window and then using quite a bit of washing-up liquid to lubricate, feed the trim into the channel. You have to be careful not to force it as the trim is only alloy and will bend..
.Once the trim all looks nice and seated, refit the rubber to the glass and then refit back into car. Remember to put a piece of cable in the rubber channel to help lift the rubber over the metal lip. Use a rotary motion rather than a straight pull, it helps in preventing the cheese-wire situation happening where you can easily damage the rubber. Have fun!
