Sound coming from rear shock

I have a 2002 Kia Sedona mini van with about 143,000 miles on it. It runs great outside of a noise I am getting from the rear driver side wheel. When ever I go over a bump I get a clank sound. Took it to the dealership and they told me it is due to shock, but that the shock is not bad. they said that a rubber piece on the shock and mounting area is missing and that the metal sound is coming from where that rubber piece would be. They took me and showed me and at the top of the shock where it attaches to the car there is no rubber and when they pushed the car up and down I could see the the two pieces of metal would hit and make the sound. The dealership said they saw nothing wrong with the shock itself and feel it is safe, however they were not sure how this rubber piece feel away.

Does this make any sense?

So how much did they quote you to replace the rubber piece?

nothing, said it was no big deal and when it’s time to replace the shock the noise will go away.