Hy Lou54Chevy3100, welcome, it's kind of hard to tell in the photos, but it looks like you have two primary shoes mounted on the same backing plate in the first picture. I don't think that alone would stop the drum from going over the shoes, just something to check. In picture two the rear shoe is not tight to the anchor post, find out why that shoe won't sit tight to the anchor post, hope that helps.
Agreed. One show will have less friction material as far as covering the full length of the shoe. One for each side of the truck. As mentioned, primary brake shoe. If you are not paying attention, it is very easy to get both primaries on the same side.
