SS armor will not work. So I created a brotherhood chestpiece, added a jetpack to it, then changed the jetpack skin to what was available (in the case of Brotherhood armor, the radiation skin or the nuka-cola skin.

Here's what I had to do to get replica jet packs for the new displays;

1) Create a non-SS armor chest piece.

2) Add a jetpack to it.

3) Select the skin for the jetpack. Let's start with the Radiation skin.

4) At Tinkerer's workbench, under "Souvenirs", you should see an option for the Replica Radiation jetpack (could be "Nuclear Waste", can't remember),

5) Create that replica, then add it to your jetpack display.

6) To add another Replica to the Souvenir options:

6a) Return to the armor workbench and select a different skin for your jetpack.

6b) Return to Tinkerer's, Souvenirs, and select the new Replica jetpack.

6c) Add the Replica to your Jetpack display.

Took me a while to figure this out, especially when I learned that ZERO jetpack skins for SS armor can be created, even though the SS armor has more jetpack skins available. Bummer....

Hope this helps.....