1968 barracuda trim mount washers?

So the final pieces of the puzzle for my 1968 Barracuda is the rear trunk panel pieces. They should be coming back from Classic Trim Restoration next week so I'm looking at my mounting clips and notice some have a foam like washer I assume to help waterproof and prevent rattles. The lower clips have what look to be small leather? washers for the same purpose. What are you guys using here or is there a source for these washers?

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