well,i hear that the actual bearings are 52100 but the races can be case hardened. but that's hear say i nad a drawknife out of a outer race of a compound bearing and it worked well. but it is a bear cat to work. but don't let that discourage you, some ways to tell (from my experience)if cracked,it will crack across the race,or it may chip if driven out. or if you have to wash it out you will have to blow it in two,anyway i hope this helps ya out,jimmy