I’m a bit confused by your Ebay X3 auction. Does the picture on ebay showing the X3 with the spindle upgrade? Scyan posted some great pics on his X3 mill but that spindle has a Jacobs chuck and not the one you have on your website or on ebay. The Jacobs chuck (or something like that) is the standard and the one on the pictures is the optional spindle upgrade?

The Jacobs chuck is standard on all machines.

The unit on ebay, for now is a standard spindle (non-G code controlled, 1750 rpm limit).

Starting in a week, all machines are standard with spindle upgrades.