I recently acquired a non-op 49 cub. Overall it appears everything is present and mechanically functional. There is a hand crank that works and spins free as well as a battery box (with a missing top). I believe this is a 6v as it appears original, but how should I confirm this? And is there a recommended size for a 6v? (I saw a recommendation for a '48 to use BAT7244, so I'm guessing it is the same)