This is a drawing of a GM17 gearmotor that you can use in your designs. Its easy to take the dxf and put it in your drawing to easily add mounting holes, etc. This little motor is pretty beefy and very nice.
Open it, import it to your design. Change the mount holes to the layer you want them cut into, and leave the motor in a 'Motor' layer as a helpful reference for where the motor will be positioned.