Vinyl top molding holes....what to use around clips

On a 68 B-body the clips for the vinyl top molding push through holes in the C piller

What do you use to seal around the vinyl top molding clips to keep water out of the trunk?

I am thinking it should be the same stuff thats around the 1/4 panel extention studs, which stays soft almost like play doh. What is the proper name for that stuff and is it still available?

I know seam sealer would work, but might get to hard to get back apart again if need be.

I found rubber washers on my original trim clips. I used "strip caulk" around the clips when I put the car back together.

I did a search on 3M Strip calk http://3mcollision.com/3m-strip-calk-08578-black.html and that is exactly what I was looking for.

Thank you.