Quick gastank question

hi all! I am a DSMer and have no clue with chevy's. My bro wants to know whether or not a gastank from a 91 cavalier will fit into a same year Corsica. He asked the dealer and they said no, but they didnt look into it. They just simply said no. Any help here?? Thanks!

go to autozone and see if the part numbers are the same for each one.