... it didn't have an interior.
Mine did, sort of. There were seven seats (but no platform floor), an front control panel and a interior bulkhead that gave the model a bluge 3/4 of the way back from the bow.
My astronauts made of lego blocks fit the seat nicely. Plus it floated in the tub.
Maybe I'm misremembering in my old age. The last time I had the model was during the 70s. I know the door and windows were molded into the body and didn't open.