Quote Originally Posted by BigTruckDriver
Also I see some 9" have the pinion centered , what the purpose of this? Is it for certain style of racing? That means one axle is shorter than the other...
I'm not sure I've ever seen a stock 9" rear that didn't have a centered pinion. The pinion gear is offset to the ring gear which is in the center of the carrier. In order to have a straight floor tunnel, the entire carrier portion of the axle is offset to put the pinion in the middle of the car/truck. This naturally ends up with one axle shorter than the other. Could it be you're asking about having the carrier portion of the axle housing centered, which would in turn make the pinion offset relative to the overall housing? If so, it's most often done for appearance.