I've had the front end off the ground with both wheels off and tried everything I can to find something loose but everything appears to be solid, no play anywhere that I can find.
It's quite loud when it happens and seems to be under heavy braking or acceleration and sometimes it will knock as the steering is turned, even at a standstill, but as I said I can't get it to do it with the wheels off load.
It also passed the MOT in this condition so wasn't picked up by the testers.
The only thing I didn't replace was the drop links, but they were fine before I replaced all the other bits and I can't detect any play in them at all, and they're not that old having replaced them last year.
The ride quality though is the best it's ever been and is real magic carpet and handling seems fine too, so I'm at a loss to know what to do next other than replace the drop links again.