51 36 1 831 670 - That's the vertical seal at the b-pillar. I re-used my old ones as they were NLA when I did the refurb of my Touring 6 years ago, and, honestly, my old ones were ok.
My problem was the long rear side Trg vent window seals. I bought new sedan ones and 'extended' them. A few months after I finished, W & N started selling ones for the Touring!! (I have those now for spares).
I honestly don't know what the difference is between the sedan & touring b-pillar seals, apart from the length/height. The Touring chrome cover piece is about 8~10mm longer the the sedan version. If it's only the length that's different, then extending may be the only answer.
Try Jaymic in the UK; you never know what they might have.
Sorry I can't be more helpful.