knocking in wheel well
Pretty sure you have the air suspension in this one. One of your air springs could be bad causing one side to bottom out when hitting a bump. I would take it to a pro and have them check it out for sure. If the air suspension has been taken out, you could have a broken spring or the shock could have lost it's oil. If your air suspension is bad, you will be looking at quite a hefty repair bill. People do take out the air suspension and go with conventional shocks or struts in the rear.
the rear shock mount in trunk is worn and has some play in it causing it to "clunk" when you hit a bump. Replacing the shocks and rubber bushings(they come with the shocks) will fix the problem and improve the ride and handling as well.
Search Lincoln Mark VIII Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Lincoln Mark VIII Experts