What to put between painted body panels?

[mc1984ss]

I am about to reassemble the front end on my Nova. I am looking at the painted joints that will be overlapping such as the inner and outer fenders and the inner fenders to core support. I had thought about using strip caulk / dum dum in bed the panels. I figure this will prevent rattles and will offer a little cushion in between the panels. Any thoughts or experiences? Thank you!