I would imagine that every spindle brand could be different. Why not, after all?
Your most effective option is to strip the spindle down and inspect the bearings. They WILL have part numbers on them, and generally they follow an international numbering system. Then ... match the bearing numbers.
You WILL find that the price of the bearings can vary at least 3:1, depending on the source. They come in different grades even from one manufacturer. That is, the mfr makes 1,000 bearings and then sorts them by testing. The test is usually to spin the bearing and measure the noise: the less the better.