A few possibilities to check for the noise:
-Perhaps a cotter pin was missed and the castle nut backed off.
-Shims could have fallen out causing the cross shaft to move on the frame bolt
-Were the UCA bushings replaced as well?
Thanks.
The castle nuts are all properly tightened and cotter pins in place. The upper control arms are tight (they've been replaced in the process of trying to solve this). two different pairs of upper control arms (stock with urethane bushings, and speedway tubular) have been installed and the noise is unchanged.
Really the only thing I haven't done is re-replace the (brand new moog) lower ball joint. Everything else has been back apart, inspected, and reassembled MULTIPLE times. And it's all new.
The only thing at is not brand new on the front suspension is the stamped, factory lower control arms. I did sandblast them and install new ball joints and bushings. The spindle is stock/factory, but I have no reason to believe it is causing this (again...ball joints are tight).
I can't re-create this by bouncing the car by hand. Only while driving, so far, have I been able to do it. I think it happens mostly when the driver side lifts (sharply turn the wheel to the left).