I have everything that bolts to the Z axis carriage. The motor, controller, spindle, etc. I have all of the original pulleys and belts and motor mounts as well as (currently installed) a 4700 RPM conversion I made quite a while ago. I would assume that the 3 bolt pattern that bolts this to the Z axis is identical for G0704 so this would be an easy upgrade to a belt drive for G0704 owners.

Here is a video of the spindle at 4700 RPM...motor sags a bit but this is a big slotting cut with 6mm end mill. https://www.youtube.com/watch?v=ObcXY_5E65E

Here is video of making the new pulley. https://www.youtube.com/watch?v=T5tVSp30F-w

Everything works and is in good shape. I'm in the Dallas, Texas area if interested, or I can quote shipping if you want. Can also provide pictures.

If you want a backup, want one to play with, or you just want the 4700 rpm stuff, make me an offer.