The front differential problem that I had was a manufacturing problem from Dana. Mine was manufactured prior to December 2006 and apparently Dana knows of the defect. When mine was replaced and sent back to Dana, they confirmed that mine had the manufacturing problem. The symptons that I experienced was a slight vibration at 40-45 mph and 1500 rpms. Chrysler flew a technician to my dealer because they thought it was the drive shafts so they replaced them and it did not resolve it, then replaced the rear ring & pinion, it wasn't that, then the technician finally heard of the Dana issue with the front differential - my dealer removed the front drive shaft and test drove it to find out that it no longer vibrates - that's when they talked to Dana and found out about the issue and went on to replace it. I do not know exactly what the issue was but will find out for you if you are interested.

I have also had the TSB done for the shuddering, mine was already flashed to the latest so my torque converter has been replaced. It has been about 800 miles now and all is finally fine with my Nitro.