I bought mine off ebay a couple months ago. But you can get one from DHS Diecast. I haven't finished converting mine completely to motor drive and possibly remote yet.
http://www.dhsdiecast.com/shop/produ...roduct_id=6031
Here's a picture of mine Stepside took, but you can't see the motor setup. The gearmotor I had laying around turned the wrong direction so I added two spur gears to reverse direction but the torque made the thin steel on the Sandmaster flex popping the teeth over one another. I'm going to get a DC motor next to try with direct drive through a Lovejoy jaw coupling.
