There is a very good thread on the removal and replacement of the power steering pump - https://www.benzworld.org/forums/w140...-overhaul.html
- suggest you check it out. I followed those instructions and had no problem at all with the job. I do have the necessary tools (didn't use air tools with all of the aluminum involved) it is not a bad job.
Add a quart of MB PS fluid, blue Loctite and some rags and you've got what you need.