The seam sealer that is out there is light years better than what they were using 50 years ago. You still need to buy the good stuff, not the crap at advance auto. 3M makes really good seam sealer. Self leveling works great but not sure how well it would work on the drip edge....never tried it there.
Im pretty sure the stuff mopar used actually absorbs water. Kinda like the filler at the quarter panel seam.
