Because the lower "keyed" cable from the transmission to the power unit (Jason, thanks for the pic) is so rare and (I think) expensive and is not reproduced, I found a way to solve the problem and get this thing started. I bought a reproduced "upper" cable (power unit to speedometer) in the States and got another good used original (long) speedometer cable for free of a parts car from a friend of mine, to build one, that's fit on the connections either the power unit and the tranny. But the important thing is, that I created the "keyed" piece out of a metal hose by welding a piece of metal on it, where I can put in the inner metal cable. Squeezing it will protect it against rotating. It fits perfect in the power unit (I know, that I have to cut it). The whole thing costs less than 30 bucks. As always, I've gone a different way to fix anything about my car and I know, that you don't even like "my way" sometimes. But it works and I am very proud about it. Guys, thank you very much for your help! I really appreciate it being a part of this chapter. Especially to Jason, who's alway there for everybody.