17 High country going over bumps/turns

[highcountry09]

Hello , I got my 17 high country about month ago and I’m trying to figure out or get any suggestions on why my truck in the rear is making a noise. I will drive the truck over speed bumps , turn left or right , or when I’m turning to back up in a parking space, I will hear almost like thumping noise, clunking noise just going until I stop or almost sounds like the spare tire is rocking back and forth. I dropped it off to the dealership , they told me it was the inserts in the leaf springs but I’m wondering if anyone has dealt with this and maybe it could be something else. They told that the inserts in the leaf springs were on backorder with no eta , which I don’t know why they just won’t change out the whole leaf spring. Thank you