I stripped the spindle out of my SX3 to clean it in prep for speed up grade. I found it has a taper roller at the bottom then a single thrust under a deep groove ball bearing which seems a bit odd once I'd measured it. I found I could replace the top pair with a single taper roller better speed rating which is now limited by the bottom taper roller @6300rpm your thoughts are welcome. I did find that the thrust had several discoloured balls