I believe there have been three versions of the Twilight 2000 rules. There was the first edition. Then Twilight 2000 version 2. And then they updated this book to Version 2.2 to make it compatible ...
Science Fiction and Fantasy: Who holds the license for Cadillacs & Dinosaurs? Who currently owns the Cadillacs & Dinosaurs/Xenozoic Tales license? (Or, how can I find out who does?)