68 barracuda factory air under dash vent pad

I was told there is a pad that mounts under the air conditioning vent housing on my 68 barracuda. If so mine must have been removed somewhere along the way.
My car does have factory installed air but no pad.
Anyone ever heard of or seen such a part?
Ever since I was told this it has been bugging me that my car has this pad missing.
I hope they are not made of unobtainium.