3 Degree Shims

I have a dakar leaf pack. Can someone tell me what is the best 3 degree shims to use? Are these any good? For install does anyone have a good video?
I think this is the order I would add them in?
1. Jack under rear diff and one under the back of the truck.
2. Remove U bolts (do I need to remove the rear shocks?)
3. Lower differential
4. C clamp the leaf pack and remove center bolt.
5. Add shim and new centerbolt and tighten
6. Reverse hook everything back up.

Am I missing anything? Is there a way to do it without removing the center bolt? Thanks in advance

 

There are shims that can go in without undoing the leaf pack

 

how do you keep them from slipping out?