bearing job is needed and as I have read on some threads, this is not an easy job. I am thinking of just replacing the whole assembly with a good used one - P/N 1263503205. This is the whole control - trailing arm assembly.

Has anyone done this approach rather than replacing the bearings? I know there is a special castle socket needed to replace the bearings which I do not have and cost at least $100. I am thinking replacing the whole control assembly with a used one might be easier and might cost the same in the end.

thoughts?

I'd be afraid that you might end up doing a bearing job on the used control arm soon after installing it. That tool can be found for around $20. Do a search on Ebay for "axle flange nut socket". You don't need the expensive Baum tool for use one or two times.

I've replaced bearings and I've replaced whole corners with used parts. As as mentioned, you have to be very sure that a replacement hub has a good bearing. It's just work, but a lot of work. Given a choice between the two methods, not sure I ever want to tackle another Mercedes rear wheel bearing.

I agree with the idea of replacing the whole arm, if you can find one that has a smooth and tight bearing.
On my '91 with 260k miles, they are still going strong. But my right one has always had just a bit of play. About 15 years ago I noticed it, and I assumed it was getting ready to go. I decided to take it loose and do the fairly entailed replacement job. Well. I never got the nut to loosen. Got a pretty good castle socket at Harbor Freight really cheap, and it worked fine, followed the service manual instructions - just could not get it to turn even with a 6-foot breaker and my whole 200 pounds on it, and penetrating oil on the nut!
Wow, I still wonder if it's left-hand threads, but the service manual doesn't say it is. So, I left it alone, deciding to wait until it failed, and it never has.
But when it does, I'll probably look for a good used arm and not try to fight it again.

DG

Thank you for the responses. In my case the symptom is clunking randomly while driving at the left rear and a slight loose on the hub is all I can point to. Sway bar links are good. Just replaced them recently. If I push and pull from bottom and top of the tire with Jack under differential, I can feel looseness slightly. The right side is tight so that is why I am pursuing bearing problem

Where can I get a dial gauge at reasonable price? Can it be rented?