I agree that I didn't do a great job of explaining that part. It's pretty difficult to see since it's buried inside the frame. Basically, there is a 3/8"x4" piece of bar stock welded in between two of the rear cross members and the main rail on the sub frame to bolt to. The springs fit inside the frame in the factory bed mount bolt locations. These pictures might make it a bit more clear.That was very interesting, however you mentioned the spring mounts, showed approximately where they were going, but didn't show the finished mounts. Or, is it that you haven't done them yet?
Excellent build, been following it almost since you started it.