Trans Mainshaft Runout

Thanks for this information Jim. My measurements were taken on my craftsman 12 inch lathe using a 3 jaw chuck. Run-out has not been checked on the lathe because its new to me. I purchased it reciently. So my plan is to build a set of V blocks using 2 roller bearing on each piece. then rest the shaft in the rollers and recheck my run out. I will post pics and readings then.

At 8 thousands runout the gears will bind. Replace the shaft

I understand zero runout is desireable but what is the replacement runout on the trans long manishaft? Mine appears to be 8 thousands but I do not have a set of roller V blocks yet. Thanks all.