I have a 1/8 pan car with a ball diff. I was referring to my Evolva or any 1/8 4WD road car. I know on another forum(RC Monster) a gentleman by the name of Serum converted a Serpent and equipped it with a rear ball diff and it worked fine. Why would it not turn with a rear ball diff? With a solid rear end you're not turning as much as you're sliding. Don