This post was edited and cut very short. It was originally a solution I posted to the dreaded leaf spring clunk- whereby pieces of sheet metal were inserted between the isolator and spring.

It worked good while everything was hot and dry. After a month or so of good rain and moisture, the noises came back.

I have resolved it once again, but this time I replaced the isolator pads. Truck is now nice and smooth, and quiet. It made all sorts of clunking and knocking beforehand- when crossing or entering a driveway, when turning especially tight and slow, and even when shifting across forward gears and into reverse. Nice and quiet for now, we will see how long the eBay isolator pads hold up for.

 

Awesome, neat trick!