JIm

The distance between the journals on the 405� is less then that of other SB lathes. I never did find a spindle from another SB that will fit the 405..... (I have an extra spindle for sale).� You did the right thing by replacing the whole head stock with a side oiler on the 405.� I never tries the needle bearing replacement for the thrust bearing. I do not want to risk the spindle or the journal.

I used needle thrust bearings on a 1914 13" Sears Expert, made by South Bend. Due to damage from it not having any sort of free spinning thrust washer, I had to mill the ends of the bronze bearing shells flat. Another problem with it was the thrust ring on the pulley was held in place by only two short pins 120 degrees apart. The bearing end wear had let the ring move and spin around. I replaced those with three set screws.

Essentially the whole thrust support setup had to be reworked. After it was done, with the needle thrust bearings, it was a very nice running spindle that made beautiful cuts in all directions. The needle bearings allow for zero end play on the spindle, so nothing can catch and pull the spindle toward the tailstock.
That's especially helpful when facing a piece with varying density, the cut is smoother.