The 9670SV is a high voltage servo that can accept 7.4V. I wouldnt advise using this servo unless you know your ESC can deliver and your receiver can accept 7.4V.
Another thing is this servo uses all plastic gears. One bad crash and you risk stripping the gears.
Savox makes pretty good and inexpensive mini servos applicable to the 12th. The only down side with them is the output shaft does not necessarily align with most typical mini servos out there. You would either need to find a chassis with slotted servo mounting holes or widen the servo mounting hole on the chassis to ensure the output shaft of the servo is perfectly centered.
http://www.savoxusa.com/Savox_SH1257...avsh1257mg.htm