Guys, I am working on the cowl area. At the juncture of the top front edge of the cowl and the top edge of the firewall, the two metal edges come together and there is a groove that is filled with a black caulk-like substance. On my 79Z this has dried out and cracked and I have removed this stuff. So what is it? It doesnt seem to be dumdum. But I want to refill the groove and make it look like it did before (without the dried out cracks of course). Thanks for all replies! I love this site.