IMHO, this is is a must for setting the end play "Easy and right".
That's called a dial test indicator. I got one on ebay from "800watt" for about $12, or another seller has one with magnetic base for about $20, not much more than a package of plastigauge. Some of the cheap ones have metric scales (the 0-40-0 ones). No it's not a Starrett or Mitutoyo, but it's good enough for this job.
