You can try searching for tank drive ESCs (Electronic Speed Controls). Look at websites that sell electronics for robots. Scorpion is good, Barello ANT controllers and Dimension Engineering Sabertooth. Most of these are designed to be used with a standard ground radio, I don't know if they will easily interface with Hen Long electronics. I replace the HL electronics with a standard 5 channel radio and used the ANT150 and ANT100 controllers for the track, elevation and turret rotation.