http://www3.towerhobbies.com/cgi-bin...&I=LXBEK7&P=ML or
http://www3.towerhobbies.com/cgi-bin...?&I=LXBEK8&P=7 in the Futaba brand depending on the connector of the other radio.
Tower also has their own line of cables slightly cheaper at the bottom of this page
http://www3.towerhobbies.com/cgi-bin...=trainer+cords Just pick a cable to suit your needs.