[Lmackattack]

Havent found a solid solution. My box sounds about the same size as yours and will also hold 3/4 of a 5 gallon bucket. I am Also trying a small screwdriver motor right now. It has 2 planetary gear reductions limiting the revs to a max of 350rpm and puts put 110 lbs of force. Problem is the out put shaft is not set up for adding a gear. I will need to have something machined. I'm also clueless how to figure out the needed power to lift a fully box of sand or dirt.

What size screw driver motor are you using? Does it have reduction?