We pull a 27' fifth wheel (~9400 lb.) with our 2012 F-350 SRW CCSB. We first installed a MORryde pin box to reduce chucking. I'd say it reduced the horizontal chucking by 50%. MORryde doesn't do anything for vertical motion like the other pin boxes do, but it doesn't cost much and works pretty well on the horizontal motion. However, we love the MORryde 4000. Wow, what a difference from before with a Lippert Equa-Flex Equalizer (which didn't seem like it helped at all.) If doing it again, I would install the MORryde 4000 before I did anything else because it made such a difference. In addition, I would also assume that the jarring to the trailer is dramatically reduced. In our case we always would have to re-position the microwave plate after every trip--after the 4000 installation, we only have to re-position the plate about 1/4th of the time. The 4000 system does need a lot of vertical motion so some trailers need a sub-frame installation. We had MORryde factory Riser Tube installation done on our trailer to get the clearance (that we also needed to level the trailer.) We still have the jolt from the pickup truck axles hitting tar bumps and bridge transitions. A pin box that allows for vertical motion might help reduce that, but I'd absolutely start with a 4000 system before doing anything else because it is so effective at reducing shock to the trailer.
