The "others" could be considered pre-production cars that could not be sold and were probably scrapped after initial testing, show-car use or similar.
2/11/2010: Note: Mitsubishi CAPS indicates there are 3,005 E39A models, so that would support at least 4 scrapped or without VINs.
Trim codes:
1991
A70 is sunroof, stock radio
A71 is sunroof, EQ/input
A74 is sunroof, CD
A80 is stock (no sunroof)
A87 is EQ/input (no sunroof)
A88 is CD (no sunroof)
1992
A71 is sunroof, stock radio (EQ/input)
A72 is sunroof, CD
A81 is CD (no sunroof)
A87 is stock (EQ/input, no sunroof)
You can find more
Mitsubishi Galant VR-4 information here.