Interesting. So where are the drain holes?
More accurately I should have said drain openings. They sometimes were "holes" but often small arches along the bottom of the door skins where they meet the inner door, where inner fenders meet outer, etc.. There's no one map because every manufacturer had their own way of doing it. If we were together with your truck on a lift I could point some out to you. Anywhere rain water could get inside structure there were likely drain openings to let the water out. Most I've seen were much smaller than Kevinski mentioned. They don't need to be large to let water out so most I've seen weren't. That made them easier for the thick undercoat to plug.
