You need a shim pack and a dial gauge for depth if your doing it yourself and you need a nice long bar to get torque on the pinion bolt and able to get the car a nice distance off the ground.
your bearing should be fine, i've compared new bearings with ones that had 38k on them and the look pretty decent. It's more for precausion, i mean think of the stock bearings that dont go out after 150K+ on stock axles.