Interior Caulking on '69 Chargers

[69chargerrt]

While replacing my headliner on my '69 Charger I noticed with the old headliner removed that towards the back of the roof and just in front of the rear window there's a reinforcement piece that runs across the roof (it's the piece where the back end of the 2 headliner bow wires anchor to). In between it and the metal skin of the roof itself I noticed a thick light grey bead of what I would guess was caulking running along the width of the roof. Now this caulking that was in there was so old it had hardened, and almost literally fell on my head when I poked at it. 

There's no join seam on the roof skin at this point, so I'm guessing it's there to keep down any rattles or squeaks between the bracket and roof skin, and I'd like to replace it with some new caulking before installing the new liner. What would be suitable for this that's readily available?

Thanks!
David

[SFRT]

3m seam sealer....rules.