A group of us were trying to build a small tank for a competition that could climb over 4 x 4s. The vehicle has to fit in a box that is 370 mm x 165 mm x 165 mm and that lighter it is the better, as we lose points for every gram it is, so we were hoping to keep it under 5 lbs., just for a weight estimate. Any suggestions on what size of electric motor that we should use as far as torque ratings and rpm go? We were planning on using two motors, one for each tread. Also, the cheaper, the better. Any help would be greatly appreciated.