Here are pictures of the saddles I have.
After looking at the parts and the installation manual, it looks like the following:
These go below the factory perches, between the axle and the leaf spring. Uprights towards the outside of the axle, u-bolts go on the outside and don't pass through saddle, bolts go through the holes in the factory perches,
then the spacers are installed
, then through those two holes in the above saddles towards the inside of the axle, then the spacers are installed, then through the backup plates.
Backup Plate w/ dimple(from instruction sheet)
These go below the leaf springs.
Factory leaf spring clamshell.
No, you wouldn't keep using these, because the leaf springs will be under the axle.