Good morning to all from a snowy newfoundlan.

Over the past few days, the truck has developed a medium frequency noise which appears to be coming from the rear end. This noise is more pronounced in the 50 to 60 kph (30 to 40 mph) speed range. I have just taken the vehicle for a test drive and afterwards checked for any signs of heat but all seams normal.

Any assistance in isolating this problem would be of very much appreciated.

 

These trucks are hard on U-joints. Mine felt the same way, and I tried feeling and looking at the joint and it looked normal. I finally decided to pull the four bolts that hold the shaft to the pinion yoke and I knew immediately it was bad. You have to drop the shaft to find a joint going, unless it is really bad. Also check the carrier bearing in the shaft if it is a two piece. Good luck.