Kregus,
Looking at your pictures, I believe that your springs have indeed been modified. The thick spacer plate is definitely an addition, and it maybe replacing a thinner "leaf". It also appears that several of the leaves have been re-arched. I'll try to remember to look at my truck tomorrow and grab a couple of pictures, but off the top of my head I think there are 18 leaves in the rear spring packs. I know all of the leaves in my spring pack are the same thickness, and that there are two "groups" of springs (the main set are all together and have the same arch, and the "overload" set also have a similar arch but are separated from the main by a couple of fairly short leaves.
I went through my photos and found the two best shots I currently have of my rear springs and put them in my signature gallery. They don't show quite enough detail to get you what you need but maybe they will help.
