Adding air bags to tow vehicle questions.

I have air bags on a GMC 3500 SRW. They do a great job of leveling the truck under load, which does help some with the ride. As far as fore & aft movement of the king pin in the hitch, I never had that issue, largely because I have a B & W Hitch. As far as the up and down movement, there is not much you can do about it because the truck wheels are not going over the same bump at the same time as the trailer wheels. I added a Fifth Airborne pin box and it made a significant difference in ride quality because the airbag and shock absorb-er greatly soften the ride. You can look in the rear view mirror and can see the the up and down movement between the truck and trailer, but with the 5th Airborne, you just don't notice it.