What is this noise/clunk in my drivetrain? Slip Yoke?

[mattbta]

Great Video !! Now I know what mine is doing every time I come to a stop sign. '00 Tahoe 292,000 mi. Original U-Joints, Yoke, Bearings. Mine will need everything you just had done.

Honestly, I would try ujoints first. The parts were $40 and the labor was $40. If I didn't have a bunch of whine/howling that's what I would have done first without opening the rear diff. Good luck.