Clunk from rear airlift suspension

Hey guys,

Installed an airlift rear suspension on the rear leafs of my 2012 DC Trd, in conjunction with the 1" spacer that is part if my leveling kit. It seems that whenever the u-blot that holds the bottom plate of the airbags to the rear leafs has any tension on it whatsoever, I hear a clunk when the truck stops and starts It also does it over some speed bumps and other rough spots. Anyone familiar with this, and how do I cure it?

Thanks