Check the tie rods on each side, make sure they're adjusted close to each other, guard against some errant alignment tech that pushed one side way off and then pulled the other in to adjust for it. If they're pretty close and the wheel is still far off center then get the wheels pointed dead straight. The splined u-joint connecting column to rack can be pulled off and the little plastic alignment piece can be reset to center. Make sure the steering wheel is straight and then re-attach the u-joint. That should center the steering wheel to the rack.
The spec for the standard length on each side is on page 98 under "Steering" in the FSM and the procedure for resetting the rack is explained under the rebuild section.