Funny this popped back up, I was cleaning up some bearing and noticed that one was MRC 308 SG10 all engraved markings and one was typical stamped MRC 308-SG10, but the 10 was crossed out and marked 8 via an engraver. So what is the difference between SG8 and SG10? Also trying to understand how these bearing widths effect the wear on the cluster with the bearing retainer and selective snap ring.