I have replaced the caster ball joints and bushings in my 560SEL. This should be the same. Are you also replacing the body mount bushings also, or only the ball joint? I used a small arbor press to get the caster ball joints out of the mount, and pushing the new ones in was a chore. Try a large hose clamp, (4 inch diameter, +/-), to hold the exterior part of the castor ball joint compressed, while pressing the new one into the mount. You will see what I mean. The bushings that surround the bolts holding the mount to the car are easy to push out and push back in, with some lubricant and either a clamp or arbor press again. The CD Rom manual recommends a special tool for this, but I did not use one. I seem to recall I did this myself pretty quickly, less than 2 hours a side. But I could have rosey memories. Check my old posts. I am sure I posted the results someplace, after begging for help on this job.
I have not done the lower or upper ball joints in my car yet. Who is this IMPCO that rents tools? Are they local to Ohio? I appreciate this information. I will need to rent the ball joint tool eventually, I am sure. I do not know if Fastlane rents them, but I think not.
1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)