Correct. The C303 is the civilian version that is a little different in that it is 12V and the few examples I saw pictures of had slightly different features. These were often municipal or fire vehicles. The TGB or Terrangbil version is the military 24V that came in both 4x4 and 6x6 versions with 4x4 hard-tops, soft-tops, and tank destroyers, and 6x6 troop carriers, cargo haulers, and ambulances.
Cheers,
Greg