04 ram with cummins started making a whining noise, especially when coasting down a hill with foot off accel. Also does it when you let off when going down the highway. The noise slows down as the truck slows down. Almost sounds like when its in 4x4,but its not. Could front end be locked in yet? Although it doesn't hop when turning corners as you would expect. Or is something just going out like the torq converter? Truck has 75k on. Thanks for any info.