1989 420 SEL

I have started replacing various steering and suspension components in the front end to relieve the constant barrage of noise that I hear while traveling down the road. To date, I have replaced:

- tie rods
- guide rods and mounts
- steering damper
- eccentric pin
- shocks
- lower control arm bushings
- idler arm (repair kit)
- ball joints
- drag link
- subframe bushings

These needed to replaced (many of them were original) and there were some improvements in the noise. I searched the posts and found suggestions to replace the upper control arms and the sway bar bushings. I purchased both sway bar bushings - those at the upper control arm and those that rest at or just inside the firewall. The only post I found related to the latter bushings discussed removing the sway bar which I have no intention of doing. Can anyone provide some insight on what might be involved to replace these bushings?

If the noise persists after these parts are replaced, are there any other suggestions for eliminating the knocking and clunking noise that I keep hearing?

Thank you in advance for any information.