I can sense your frustration. When we hooked up our new to us 5er we were shocked at the chucking. We are talking about heads bouncing off headrests and my wife having to hold her chest. My trailer did not have a replaceable pin box and the Torflex axles did not allow shocks. I tried the Bilstiens, no help. I had to face up to the fact that my trailer for many reasons was creating both bouncing and chucking forces and my B&W hitch was transferring them very effectively to my truck.
I did my research and as posted previously ended up with a TrailerSaver TS3. Fortunately, bouncing and chucking forces are timed events. As the front of the trailer is pushing down it is also pushing forward. The TS3 has a high hinge design so as the hitch head is pushed down against the air bags the head also rotates forward eliminating the chucking forces. As I see it, this is the major difference between the BD3 and TS3 hitches. The TS3 is an ingenious design and it works. As I go over bumps now I still get the impacts from the truck tires, no getting away from that. However, I feel nothing as the trailer goes over the same bumps.
I know you are probably real tired of writing checks. Hensley has a money back guarantee if you aren't satisfied. I have no ties to them and am just a very satisfied customer. Leaving in a couple of hours on a trip. Looking forward to the tow.