Identify unknown rubber in front shock mount

[z28-50]

These are pictures of an unknown (to me) rubber cushion in the front upper shock mount of a 1995 Camaro.
The unknown cushion is between the dog-bone and the body.
The flatter part or bottom of the cushion sits on top of the dogbone.
The ring fits in to a recess of the body.
Is this rubber orderable?
What purpose does it serve?
I have all the other parts new and hate to put this back in used.
You can click on the pics for a larger view.
The first pic has what looks like a part number of 22112178. Part number does not show up on any parts fiche.
The last pic shows the order of assembly.

[Boost Addict]

Pretty sure it's an insulator. I had to change one of the 2 (forgot which one) pictured when I did front struts on my car because I melted them. Check your parts store and tell them you need an insulator for the front struts and they should be able to find it. I went to my Chevy dealership and couldn't get either one.