In the XTM, I believe the two servos are the same stock. I never really paid attention to them. They were the first thing I threw out of the bug
Your steering servo needs to have a good wheight and speed rating.
Your throttle/brake servo needs to be fast, but not quite as strong as the steering servo.
Check these out:
http://www.amainhobbies.com/index.ph...ssories-Servos