When I start from a stand still, such as a traffic light, at the instant I press the accelerator, I feel a slight thump. Feel like maybe the clutch in the transmission engaging, or slack in the driveline? I have read of something similar on 2500HD, but wondering if any dually owners have this same sensation and know what is causing it?

I don't have this problem on my truck, but on other trucks it was caused by a bad u-joint.