Rain gutters and body seam sealers

I am working my way through a resto of my 63 Dart 2 door post and am close to epoxy primer and have a couple questions. I have removed most of the old tar based seam sealer from the inside of the car and plan to redo it once the car is in epoxy.

What I am trying to figure out is what it is they used in the rain gutters and on the seams on the outside of the car? The sealant in the gutters is separating (shrinking I assume) from the roof and I would like to clean it out and replace once the car is epoxy primed. Also there is a sealant used in numerous places on the places where panels were joined (not where it was leaded) like in the rear bumper area and around the door openings and where the rocker meets the quarter panel.

I am pretty sure it wasn't bondo but could be mistaken. Any input would be appreciated.