Free way hop...can be common with certain truck trailer combinations on certain well used concrete highways.
There is a whole list of things folks do to help their combinations. And what works on some does't effect others.
Many folks with severe free way hop (chunking) go with some type of air suspension pin box.
Some have moved the aux upper over load spring pack so its not as aggressive.
Others may change to a larger diameter tire on the truck.
I fixed a chunking issue on on one of my 3500 DRW trucks by moving the trailers spring hangers aft by 2". The other four 350/3500 DRW trucks pulling the same trailer with no chunking issues before or after the axle move.
Good luck on your search as it can be a very aggravating problem to get a handle on.