I get the same occasional 'click' in the steering when going over bumps. I have tried tightening the steering box a bit, but think it could do with a bit more.... I haven't done the intermediate shaft yet, but it's on the list to do.
I've also heard that the splines in the steering column itself can wear (on the bit that telescopes outwards) and that can also cause excessive play in the steering. I have a spare steering column kicking about from a vehicle that was stripped for parts, so I was planning on swapping it out at some point just for the hell of it to see if it made a difference...
'06 4.2 Supercharged Black/Cream "Jess" -- Bought April 2021 (NZ)
'01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
'99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
'95 4.6 HSE Epsom Green/Tan -- Traded June 2008