Interesting timing for this question. I've noticed with the temps dropping by me that in the early morning, my Dakota seems to shriek, for lack of a better word, at certain speeds/rpms. It comes and goes until the truck warms up and at first I thought it was wind since it seemed to happen at about 30 mph, and went away if I sped up or slowed down. Yesterday morning, for what ever reason, I decided to step on the clutch instead of changing speed and the noise went away almost instantly, so it looks like it *is* clutch related, but I have no idea what beyond the cold at this point.