Rear Strut Loose at Upper Mount

I've got Bilstein 5160s in the rear. They were installed by a good shop at 12,000 miles around 1.5 years ago.

The truck has 19,000 miles now (mostly highway).

Started hearing a knocking in the back, located the noise as the rear driver side strut.

The nut is tight, it just looks like some sort of bushing came out (but I'm unclear as to what to buy to replace it)

I found a Bilstein rear Strut washer kit that has a bushing but I'm not keen to tear it down and not have a better idea what's going on.

Based on the picture below, do you all have any thoughts?

 

What does the bottom bushing look like?

 

Looks fine (to my eyes)

 

I've never installed 5160's myself but, i'd try tightening down the nut some more. Usually the top nut is torqued until the bushing squishes to the diameter of the washer.

 

So I was inclined to do that, but only got like 1/8 turn on it. I'm afraid to wrench on it anymore

Also noting that the passenger side nut is basically the same distance down from the top of the bolt.

 

It’s missing a lower washer

 

I'm thinking that must have broke? I've been driving this truck for a while and this noise began quite suddenly and is pretty noticable. Every little bump in the road makes a noise.

 

So I'm looking now and I think what happened is the bottom bushing blew up. I think I can see pieces of it here in this shot.

My hope is that I can buy this B4KT1Z008A00 bushing kit and it'll be all set.