I know this might be a brand name thing but what does the drive shaft(the thing comming out of the motor) look like. I don't have mine here and I'm trying to look for wheels. If I'm picture this right they are sorta rectangular, I was just wondering If anyone new, but they are probably all different. Thanks

 

By their very nature, most motors use round shafts. Often, manufacturers will provide one or more "flats" on the shaft to aid in securing an anti-slip drive coupler or mechanism to the shaft, but equally often, the shaft will simply be round in cross-section.

Generally, drive couplers will be secured to the shaft via set screws through the coupler body. If a shaft has flats provided, the intent is for the set screws to be tightened onto the flat, thus providing a more secure attachment. Many couplers will offer two set screws, located at 90° (to each other) around the coupler's circumference.