I've acquired a 6040 CNC from my father and working on trying to get it setup and dialed in. It already has some upgrades to it, it's running three Gecko 251X drivers for the XYZ axes through a PlanetCNC MK3/4 controller. I've spent the past several day trying to research these stepper motors, and have even sent a message to what I believe was the manufacture of them, but hadn't heard anything back and not really holding my breath.

The info on the steppers is:
AnChuan Electric (translated from the Chinese text)
1.8° 3.0A N1604

The main thing I'm trying to find out is the mH of the stepper so I can calculate what voltage this stepper is looking for. I've come across some other with similar part numbers but with a 14S/8 at the end which say it's an 8mH motor and capable of 90 volts, but mine doesn't have that, and I don't have an LCR meter to readily check the impedance of the motor. It's currently running off a 24vdc PSU, but was trying to see if I'd be better off with something higher since my Gecko's can handle up to 50vdc.
I beleive they're semi common on some of the Chinese 6040 CNC's, I just haven't been able to find much about them to really try and get them dialed in.