US Smooth Seal ESB Cards

[DMGSROTJ]

Hello all, I am trying to gather as much information as possible on US smooth seal ESB carded figures, particularly 41 D-Backs with an "S" factory code. I have a Vader MOC that I"ve been having some trouble gathering info on. Seems they also tend to have numbered bubbles. Anyone out there have any or know anything about them?
Thanks!

 

[spoons]

Only that the 47 backs seem to have a lot of smooth seals. Not sure abut any other issue

 

[DMGSROTJ]

Seems like they become more prevalent as they began to transition into ROTJ. Here is my example.