Thanks Bill, Mark, and John. This was exactly what I was looking for. Those sources for modern brands of primers and the steps of application. Lately, I have noticed several restored Z's with mostly grey sealer on the under side. Of course, they would be black down the firewall, and starting under the bottom to roughly the rear of the bell housing, and then grey sealer from there on back, and then the body color over spray on the sides. John, Was there any differences in "the way the plant did it" in any other time period, or was Bill and Gary's example "the standard" all the way through production?