I'm kind of taking a stab at this, I'm not sure if you ment that the steering is reversed or if your having trouble keeping it under control. But here goes both answers,
1- When you punch it the right rear tire is hooking up better then the left, loosen the slipper and tighten your diff properly.
2- If the steering is backwards, go into your transmitters program( hit both left buttons on JR ) and reverse the steering direction.
3- the third thing that might be your problem is when the truck starts to turn left, your feeding in the counter steer (right) too much, inducing the over steer. Try lowering your duel rates or travel end point.