You certainly can get lucky and just change the ring and pinion and not have to change the bearing spacers or pinion shim depth (I have many times and it's still in spec) just obviously check to make sure it's in spec, I typically do new bearings if they have a lot of miles on them and then just the crush ring and check from there.
As stated be careful once the crush ring starts to go check it very often for the rotational torque resistance, and a really good tip, once you hit the target rotational torque resistance tap on the front and back of the pinion with a flat punch and hammer. This allows it to settle and will lower the rotational torque resistance, if you go over that spec tapping the pinion is a saving grace.