If you are mechanically inclined you can do one thing quite easily and I bet it will take care of the problem. I had the "clunk" when taking off from a stop. I got together some rags, couple of good sized zip ties, spline grease(Grade 2 chassis lube is fine), a scribe to mark the shaft halves for re-install and necessary hand tools. Make sure the truck is chocked in place on level ground. I mark the shafts, removed the boot metal band, removed the two bolts that secure the carrier bearing to the frame crossmember, as you lower the shaft, it will seperated at the yoke. Clean the old grease off of the exposed splines, apply a liberal(only good use for that word) coating of grease to those splines and carefully reassemble the shaft, ensuring the splines line up as they were when taken apart. Tighten up the bolts for the carrier bearing, slide the boot back over the slip yoke and secure with the zip ties. Take the truck for a ride, and see if this took care of the problem, it did for me.