Recently I've developed a vibration. I'll do my best to explain.

If I let off the go pedal the vibration will be there, but if I accelerate then hit the clutch before the truck has a chance to lunge forward from the compression the vibration won't be there. Feels like it happens when something is thrusted forward. Seems to be there at all speeds. I checked my rear end and the fluid looks like new. No play in the drive line.

Any thoughts?

Kris