Yesterday I was Lucky.
I could buy the following sets:
https://www.brotherstrucks.com/prodinfo.asp?number=CPSK059
and
http://www.brotherstrucks.com/prodinfo.asp?number=SSK4759
It was almost for free so I would have been stupid not to take it. The set is completely new. The guy is going to sell his truck and was happy with some money for the set. The money I had to give for it would just cover the shipping costs for such a set from the US.
I think there are some good parts in it which I can use for my idea on the power steering for the 3600.