As the title mentions, my 2008 Suburban has developed a clunking noise at different speeds when I am driving. I replaced both upper and lower swing arms and have looked at the internals of the differential. In doing so, I have found no loose parts which includes the ring and pinion. The axle seals are not leaking. And, I have checked the spring loaded retainer that keeps the spare in place that hangs under the backside of the frame. There is some back and forth movement on the driver side wheel/axle when I grab the wheel and push and pull on it while it's on the ground. Would you say that the retainer clips that hold the axle in the spider gears is worn? I can't physically see or hear the clunking when I have it up on jack stands. The rear end is a gt4, g80 differential with 3.73 gear ration. I had a new differential and ring and pinion replaced when it had just over 200,000 miles on it. It's closing in on 500,000 miles at this time.