I got this seat as a extra part, with a 1986 K100RT I purchased. The guy told me it was a "low" seat for the K100 and K75 bikes. The pn on the seat is 52531308113, but I can not find this pn on either K100RT or K75 RT BMW parts fiche. I hate to throw it away so Id like to identify what it is so I can sell it cheap or give it away. I no longer have the bike. Any ideas?