I've chimed in once before on your sled but have since had a simular situation. I know you had your DD apart, but did all bearings get checked? My 6203 went at 700 miles, but when it went just the cage came apart and it was a noticable grinding rumble from the clutch side, most noticable when not in deep snow. I have since tried two different bearings, and each "sounds" different. It did not happen to mine but the cage parts can do damage. Also when just popping the cover everything looked fine, the back bearing seal appeared ok and all the cages pieces were down behind the planatary. It was not until I pulled the bearing that the damage was evident.
Your dealer would have caught that but for the others out there.....