One problem related to differential unit has been reported for the 2001 Dodge Ram 3500. The most recently reported issues are listed below.
2001 w3500 Dodge 4-wheel drive front driver axle lockup. Had input shaft failure occur during snow storm which caused the pinion and ring gear to lock together. When this happened the front end would not turn. Luckily happened at low speed without loss of control or collision. Truck has ~17500 miles on it and Chrysler would not cover it under warrantee. I have digital photos of the failed parts if you can provide email address I can submit them.