clicking noise

[Throbbin Rods]

I have a 2002 Suburban 1500, 4wd, 5.7, auto trans. 214,000 miles. Transmission had a complete rebuild in August 2015. Last few days when driving slowly (5 mph) there is a rhythmic clicking or ticking noise coming from the center of the vehicle, best I can tell with my limited hearing. Noise is variable with car speed. With rear axle on jack stands in gear and idling, and my kubota backed up to it for safety ,sound is still there. All U joints appear to be fine, they are tight and there is no sign of fresh rust at the bearing caps. All axle boots are fine, no holes or anything else. I originally thought front hub assembly but the jack stand test rules that out. Not sure what the heck it could be. I would be very grateful for any thoughts or suggestions.
Thanks,
Bill

[j cAT]

so with the rear wheels off the ground turning you hear clicking . I would drop the rear drive shaft . not all that hard to do . just be sure to put back in as a was. use some paint to mark. also place heavy tape on the bal weights to protect. you may find that the U joint end cap [s] may be seized not worn out and loose.

you have a 5.7L eng ????????