42-RST, or Rusti, was a translator droid "owned" by Bungo Bung, captain of the SoroSuub freighter Chubby Gundark.
Rusti was a Plintep Cybernetics Corporation RST Model Translator Droid designed by the Mephout. She was given to Captain Bung as a gift, officially as a reward for services rendered. In reality, the Mephout were getting rid of obsolete technology.
Rusti served as translator and co-pilot onboard the Chubby Gundark. She was indirectly responsible for Bung establishing the Great Bantha Breakfast Biscuit Run when she off-handedly commented that he should fill the cargo hold with them and take the biscuits to the thousands of people in the Galaxy that had never tasted them.
Programmed with a female personality, Rusti served as Bung's co-pilot, and didn't really consider herself his property. Like many RST droids, she had developed several quirks, and was sarcastic. Her life preservation programming was also modified, and she attempted to escape from the Giant Amorphous Bantha Breakfast Biscuit.
Rusti's only canonical appearance is in Star Wars Adventure Journal 11 in the story Bungo n' Rusti Get Carry-Out. However, she has made many appearances in the unofficial and non-canon Bungo n' Rusti stories that can be found on TheForce.net.