I have a 1997 S Type 3.0 it passed MOT end of Jan with no advisories and ran as smooth as silk, however it has developed an annoying dull knock when driven over uneven road surfaces. I have had it on ramps and checked all the usual suspects drop links, roll bars etc. but can't find anything loose. If I disconnect the front drop links and drive it the knock disappears so I fitted new ones thinking this should be the solution but once all bolted back on the noise is back. Anyone have any ideas ?