I think chucking is the pull back you feel as the rv tires hit a bump and momentarily holds back before going over the bump... then when it rebounds, the push is just as rough...
I say that's what it is, but I've never experienced it since I try to get the solution before I experience the problem :)
I have a tri-glide air ride hitch and although I can see the 5er bobbing and weaving and twisting in the rear view mirror, I don't hardly feel the 15500 lbs behind me !
So you see, the upgrades didn't stop the chucking, it just is not transferred to the truck - which is all I care about...
And to the original poster, just like on any internet forum, or at any large party, there are 'experts' around every corner !!!
And some of them are very VERY pushy with their 'opinions'...
I like towing with the 4x4 - and have already used it many times...
low range in tight spaces with heavy weight really makes it easier to park.