[RC-Monster Mike]

Thanks for posting, Lars - and your English seems quite good, actually(for sure better than my German). I would like to see some body-off pictures of the truck, as it sounds nicely built.
Regarding the drive shaft issue you mentioned - turning the pillow balls in as far as possible(without limiting steering or suspension movement of course) may help, but you may also consider finding slightly longer drive cups to make sure the shaft drive pins stay within the cup throughout the full suspension movement(and steering travel up front).