I think the one Wrench Monkeys lists is probably the one you are looking for with the dual master cylinder. Advance Auto Parts here in the US also lists the same thing. They say they have it in stock, but so much is listed as in stock and then you find they don't have it. I see you are listed as being in Germany. If you want to you can send me a private message you can write in German. Or if you give me a telephone number I can call you. I have no problems speaking German over the phone. And we are planning on visiting relatives in Germany in June. I have carried a lot of spare parts to Germany in the past.
