As I don't have enough Fed or Klingon minis for some games so I add various FASA minis that come close for representation. Helped laast weekend when I wanted to differentiate D7s, which I have plenty, from D7Cs. The Excelsior makes a good Battlecruiser.
Unfortunately most FASA models are way different in styles representing ships from the movies and later tv shows or are their own design particular to the game.