You would need the Fc1212-P and AHRS-S V2 If you don't already have them.
They can be found here:
http://www.cnchelicopter.com/servlet/the-2231/Xaircraft-X650-v4-v8/Detail
UPDATE!!!! (new price/additional details)
NEW XAircraft GPS-S Module+ Active GPS Antenna (E1013) for XAircraft X650/X450GPS-S Module Set and Compass
XAircraft GPS-S Module+ Active GPS Antenna (E1013) for XAircraft X650/X450
New in Box
GPS Module:
GPS Module is used to provide global...