You can find practice materials for the listening, reading, writing and speaking modules here to help you prepare for the Goethe-Zertifikat C2: Großes Deutsches Sprachdiplom exam.
Material that can be downloaded
C2 Set of model exercises
C2 Set of model exercises -- play the listening module sample audio (37:49 min.)
C2 Set of model exercises -- play the speaking module sample video (17:30 min.)
C2 Set of practice exercises 01
C2 Set of practice exercises 01 -- play the listening module 01 sample audio (37:50 min.)