yes you should buy one to sacrifice. you'll either buy one bearing to grind a 4 to 5 crush sleeves, its your call. i vote the bearing route as its much less of a head ache to deal with!! with the sleeve route, you'll need a press to remove the sleeve and bearing and install new ones each time you go to reset the pinion depth. trust me when i say grind the bearing!! saw this done and had to be done 4 times. luckily he didnt have to press the bearing on and off each time he changed the shims on the pinion!!