It depends...
If you have direct drive AS911s, they're nearly worthless in the CNC aftermarket without gear reduction. There are smaller framed closed loop motors you can buy for under $500 a set (motor/drive/cable) that are more powerful than the AS911s, but again, you'd still need/want either gearbox or belt reduction @ $300-500 per motor. The SB controller is too slow to run them with 5:1 or 10:1 gearboxes on them, without custom programming the original drives to reduce the numbers of steps per rev. However...if you were to upgrade your controller to say a Centroid Acorn, you could put either 5:1 or 10:1 gearboxes on your existing AS911s and have a pretty hot setup. The Acorn is substantially faster and able to deal with that sort of setup. You'd most likely be on your own regarding hooking them up - but everything you need to know in that regard is in the Oriental or Centroid manual. I've done it many times. Your other option might be to put them out on Ebay etc, as this may attract others with legacy equipment calling for that exact motor/drive combo. You could also sell the control box, motors, cables to someone with a Standard who wanted to upgrade, but keep in mind, the hot setup is the AS98AA-7.2, with integral 7.2:1 gearboxes like the newer tools...so, it depends...
AlphaGearbox (Medium).jpg
-B