I think that's one of the great things about the Rebellion. They pretty much picked up whatever tech the Empire didn't use (or stole what the Empire planned on using), and used it against them.
Ya surprisingly, the RA had some leftover Clone Tech or at least that is what the notes/references point out. It all seems to appear in comics though for the most part, though its not so surprising given the RA were using anything they could get their hands on.
Guess the Empire should have kept tabs on their stuff.