Is there a novel based on part three?

I can give 1 simple answer, no. Part 3 is made up by FFC and Puzo. There's no book of it.

I think it's quite unusual anyway if a book is based on a movie, it's usually the other way around. That way a book about part III can still come, I don't see why, there would be no point doing that, but Escobar, maybe some nutcase writes it someday...

It would probably look better on paper anyways.Give it a richer plot,and not having to worry about bad acting,makes for a good book.