I have 1100 miles on the truck. It is a 05 SE Off Road with the Auto option on the transfer case. Here is what I am experiencing. I will bring the truck up to speed, say 35-40 and totally lay off the gas for a second and then quickly accelerate again. The truck will make a clunk (feels like it may be in the rear-end) as it applies power to the driveline. This can be somewhat normal for a car or truck with miles on it but being this new I would hope it would be tighter. Those who had new differentials installed, what is the symptom you experienced.