I must admit that I've never seen any spaceship vehicles.
We are talking early/mid 90's when I last remember seeing them. i haven't seen them the past few years when I've ridden the ride.
I can't seem to find any pictures of them via Google... but I did find other posts with people remembering those ships and trying to find pictures of them. (without any luck).
To give you an idea what they looked like, Imagine the bike vehicles, without the bikes on the platform.
Now using the platform, the back pillar, and the roof, build a full "back" around the pillar to connect the roof and the platform. You'd create rows of benches where the bike rows are now. the side of the vehicle would be about a typical car door height, and the front you would extend slightly to create the same general front end shape as the Spiderman Scoop vehicles. There would be some supports coming from the roof to connect to his front end, again, similar to how a car windshield worked.
For the life of me, I can't remember if each row had it's own door, or if them used a raise/swing open kinda design similar to the Jaws Boats/scoop Vehicles, etc.
I can picture them because I remember seeing them in the cycle (You know... back in the days pre-express and there were 2 lines on the inside that would actually be full.), but I don't think I ever rode one. i do remember thought that they were much easier for disabled or small kids to use than the bike seats.