I don't see any PO grinding mods to the shaft. What I see so far, is a single tooth cut on the spiral teeth for 1/R sliding gear. I believe that is cut like that to be able to get under the thin snap ring that has almost no end gaps...or it might be where the milling operation stopped, when cutting that trough? I'll look at one today. Then I see the extended spline groove which is for the tang on the thrust washer for 2nd gear, and the lengthwise oil trough under 2nd. Did I miss something in the pics? Olds tail seal number 1308163 .