I have that - at least it sounds like the same concern.
Interestingly they replaced the rack and as far as I can tell it made no difference at all. Although I did sense that the steering felt "different" initially, it still rattles over uneven surfaces and I still get the clicking noise when sawing the steering.
The dealer has put it into the too-hard basket for the time being, promising to continue researching the possible cause and get back to me... not yet though.

Your suspicion re the UJ fits the observation that it appears to be steering angle dependent; in my case about a 1/3
rd turn to the left. This might be putting the UJ at a critical position where any play will be most audible.
I did get to try this with the service manager on a new car when I was demonstrating the problem and it's also there in a new car except it is virtually inaudible. The actual component with the play is still, as I said, unidentified.