A manufacturer of heavy duty axles and axle components for military vehicles and off-highway machines selected Sound Answers to assist in identifying the source of an objectionable rattle noise and provide countermeasure/recommendations to help customer reduce/eliminate noise. Operating noise and vibration measurements were made at an independent off-road vehicle testing facility. Time domain, frequency domain, order analysis, envelope analysis, and modal FRF measurements were utilized to understand where the rattle noise (source) originated. Design recommendations were made focusing on lowering forcing functions, understanding/moving resonances. Countermeasures were also provided which increased isolation to help reduce rattle noise further.