Rivett 1020S Spindle Bearing Clearance

I haven't posted much but here goes. I am replacing the spindle bearings on a Rivett 1020S. My question is on spindle preload which is set by inner and outer spacers. I measured bearing offset by the following method. I’m looking for opinions on my method or another method for determining preload clearance.

* I ground two spacers the diameter of the inner races.
* Placed one spacer on the surface plate.
* Placed a flanged bearing face down so that it was loaded properly.
* Put the outside spacer on the outside bearing race.
* Put the back angular contact bearing on outer race and then set the other spacer I made on the inner race so that this stack when rotated settled in.
* The height was measured with gauge blocks and a Starrett .0001 indicator.
* This established a height which I subtract my two spacers, the two inner races and the inner spacer which gives me a clearance of .00235.
* The same method was used on the new bearings and the preload gap wad .00525.
* By this calculation I must ground off the outer spacer by .0029.

Also, the old and new bearings are new departures.

One other question - the outer races of the old bearings both have the engraved marking T3TT. What does this refer to?

Any help or opinions would be appreciated.