Latest ( and hopefully the final... ) update:
The new rubber all works fine, but as it is not tighteen anymore, as the original set up, there was some rattle and metal noice when I drove over a speedbump.
So I decided to test some ideas in order to make it quiet but keep the ride as comfortable as before.
The first I did was a sleeve ( in Delrin ) that goes inside the long metal tube in order to take up the play. I also did some ( 3 pcs on each side ) 1,5 mm thick nylon washers and 2 pcs ( each side ) of 3 mm thick rubber washers. Worth to mension is that my main bolt is little longer than the original.
It works very good and all the noice disapeared.
As I use soft 35 shore rubber, I use 2 pcs of 1" rubber on each side instead of one 1" and one 1/2".
The order is: First put one of the big rubber dampers in between the trailer arms. Then put one thin Nylon washer on the bolt. Then one rubber washer. Next is to put this through the trailer arms from above. Next is to put the long metal sleeve into the other rubber damper and push it up from underneath so the metal sleev goes into the upper damper rubber. Push the Delrin sleeve into the metal sleeve and another thin Nylon washer before the big ( hughe ) metal washer. Then the rubber washer before finishing off with the last Nylon washer and the lock nut. I tighteen the lock nut so itīs even to the end of the bolt.
All I can say is that I am VERY happy with the result