Dose the biped scout use 422 servos or 645s?
Neither. It needs digital 5645’s minimum.
From the bottom link:
The Servos
We are providing the walker with either Hitec HS-5475 or HS-5645 digital servos. With the HS-5475 servos the robot is capable of walking but only with a minimum weight configuration (no extra weight). With the HS-5645 servos the robot is capable of doing acrobatics like the Robo-One robots. The digital servos can be used out of the box for walking, but in order to get full 180 degrees of rotation the servo programmer will be required.
Oops! We no longer offer the Scout with 5485 servos. We need to update the website. Sorry for the trouble.