This is circling back to an old topic, but I did just finish Max Gunther's book and I wanted to add a thought regarding the color of the parachute.
As we talked about earlier, Max reports that Carla helped dispose of the parachute. The parachute was red and yellow. That information would have been told to Gunther directly by Carla as a first hand account -- not something she heard from leClair nor would it have been something he discovered by research.
However, there is more. That was not just a small part of the story. That, Gunther believes, is his piece of never-revealed-by-the-FBI information that proves Carla's story. Later on in the book, Gunther describes how a piece of a parachute is discovered and the sheriff contacts the FBI and the FBI looks at it and says "wrong color". When the sheriff asks what color was the parachute, the agent tells him that information is kept secret to help identify a true DB Cooper.
If that parachute really had been red and yellow, I think Gunther would have been correct.