What's different about 929's transmitter?

Notice in this picture that #929 (on the left) has a solid white VHF transmitter and the other two birds have a white-over-red VHF transmitter. (The VHF radio transmitters have aerials attached.) In fact, all the 2009 cranes have white-over red VHF transmitters except #929. Why?

Photo: Eva Szyszkoski, ICF