No one will have a Charger prime mover sound file as users can't make prime mover sound files, only Ring themselves can make them and I doubt that anyone has provided Ring any recordings for them to make the prime mover sound from. As to what might be close, unfortunately I can't help with that as I've never heard one. The Charger has a Cummins prime mover and Ring only has Alco, EMD and GE prime movers so I don't think you'll find anything palatable to your ears as a substitute unfortunately .
- Tim