Howdy, I think they are using a product called FUSOR. I was kind of thinking of using it along with a few spot wields. I have a good friend that is restoring a 64 Impala and he is using if for most all of his metal panel repairs.
Here is a link for the stuff.
http://www.refinishmaterials.com/ct_CGmetaladhesives.htm I hope that helps… Good luck!
