Its probably a 6" front 4" rear to keep it level. So 2 inches from the add-a-leaf, and 2 inches from the block. The top bracket in the first picture looks like a track bar drop bracket, and the other two in the first picture might be bump stop drop brackets...?
Im sure the add a leaf is meant to be used with all the factory leafs and fit where their length is in between or matches a factory leaf.