Dear 86m1028
thank you for the input!!
We checked everything, and slowly will the steering feeling better.
We changed 3 times the steering box, we tried 2 used boxes and 1 remanufactured with out success, than we found a original steering box in USA on stock, never used. And the steering feeling was better.
We find out, the pitman arm was damaged and we changed all drag links and tie rod ends and also the rag joint.
Frame is not broken, but you can see he move it self, if you start to steer, if the truck stand still.
Also the holder of the leaf springs are moving a little bit. I don't now if we can change the rivets with screws?!
now we will change the bushing of the leaf springs and will attache the steering box frame brace.
Hope than the steering felling will approve.
Nice greeting from Germany