I use the HDS-877 on my rex and am very happy with its performance. It actually has a faster response speed than the Futaba s9650 but half the torque. you can look at stats of the servo is at this link. [link]http://www.helidirect.com/product_info.php?cPath=48&products_id=435[/link] If you need more torque, then you can try the HDS-577 (I have not used this one though) the link for the HDS-577 is [link]http://www.helidirect.com/product_info.php?cPath=48&products_id=1119[/link] I hope this helped.