126 Ball joint replacement
Having done this job on my 82 500 SEL (all the joints and bushings, including sway bar-rust hidden under end rubber bushings thinned the metal too much for my comfort), I found it not too difficult--PROVIDED you use the IMPCO ball joint press.
No other way except the MBZ tool. DO NOT attempt to remove/replace the lower ball joint without this tool. It is not a straight line 'press', and you cannot pound it in/out for the same reason. Have to use the tool.
Be careful when pressing in the new joint to make sure it does not 'cock and jam or you can spring and ruin the tool.
It should pull in smoothly.
RE: 'caster'--which rubber bearing--the joint on the end of the rod?- that one is easy. The two big mounts on the aluminum casting? Takes a press in/out.
I suggest installing a thicker top spring mount (get it from your MBZ dealer) very inexpensive. That will bring you back up to correct ride height.
Lower control arm bushings? Have to use arbor or hydraulic press to get them in/out. Lots of automotive machine shops and should not charge more than $10/bushing to do it.