A system for sensing the position of a work machine or loading truck includes an actuator arm suspended downwards from a secondary conveyor of a milling assembly. The actuator arm responds to contact with the truck's tailgate or rear via motion and angle measurements detected using a linear transducer, inclinometer, rotary position sensor, or proximity switch. Based on a predetermined angle measurement, the system triggers an indicator light visible to the truck driver to indicate when to stop or move forward to achieve uniform load distribution. The system can be integrated with software for enhanced control options and requires only a power supply and grounding connection for mounting on the work machine.