[campb292]

There have been reports of thumps or knocks in the rear end for some owners of all trims. The unfortunate reality is there have been a wide array of solutions and some never even get resolution. Here is one thread discussing a variety of thumps and knocks: Thump in rear end

You will find some had it fixed by replacing a left or right maybe both rear knuckles, some fixed by installing a washer above the shock (this is if the knock sounds like wood knocking), some sway bar links re-torqued. I had this noise and one day it just went away - coincidentally after a fuel tank replacement. Some have had shock replacement - worked. Some had shock replacement, did nothing. It's also possible there are multiple different thumps and knocks in play so obviously the solutions will be different.

 

[campb292]

They are probably trying the knuckle because there is a bulletin for it and it has fixed some that had a/the low speed pop/knock whatever. Some the washers fixed it, some they didn't - it's a tough one for techs because they cant ride upside down on the car to pinpoint the noise and all noises aren't from the same source. It's an educated guess. It's actually pretty nice of them to try different parts - thankfully they can point to the bulletin to justify. Hope it works.