[What's_nitro?]

Are you looking for traction control too? You would need a system to compare relative tire speed left to right and compare that to the throttle and steering input. Then all the linkages to control the 4 servos in sync. I can picture exactly what you're going for. Were you going to use the center diff bulk as a front and rear bulk as well? That would make it easier to mount linkages, rather than modifying a normal diff case.

Errr sorry for the semi hijack...