The tone ring for the speed sensor presses on to the back side of the ring gear. When using the 3.73 gears the ring gear moves over far enough that the tone ring may not center with the speed sensor. It may be posible to shim the tone ring to center with the sensor.
Well if you live in Houston and want to change your gears...DONT go to Houston ring and pinion! He kicked me out of his shop once i started asking him if there was anything we could do about a rear abs issue ...he had no clue about any problems ....so i showed him these posts and he got mad and told me to leave ...its kinda of odd!! All i can do is laugh...im thinking about taking it Houstondrive train