Yaris 2007 sedan (auto) Transmission fluid change and rear wheel noise

[narly charley]

Automatic Toyota trans fluid does get dark... You would just flush the trans fluid with new. You can get away with a lot of miles on automatic fluid, I usually go about 75K.

The sound from the rear could be a wheel bearing. Does it get louder if you turn one way or the other? If it does, it's most likely a wheel bearing.