My right rear door panel rattles when I drive on rough road. (Occasionally on smooth road at specific speed and acceleration. But this is rare.)

I put foam (wax applicator and cut shoe insole) between the side of the rear seat pan and the door panel. I test drove the road on which I had rattle. Now it does not rattle. However, it does not look nice. When I open the door, the yellow Meguiars wax applicator can be seen on the inner door panel.
Furthermore, it is likely that someone who get into or out of the rear seat kicks the foam off.

It is not permanently attached. I put removable tape (3M Magic Tape) on door panel. Then put 3M double stick tape. Then insole and wax applicator.

I asked an indi for an estimate for door panel rattle repair, but did not get specific answer. He just told me that it is $79 per hour, however long it takes.

How much is it usually?

__________________
1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

This is pretty common on all W124's. When I first got mine, all the door panels rattled so badly, and it drove me nuts. I repaired each one eventually. Here's what I did:

1. Remove panel
2. Grind /cut off broken rivets which connect armrest to door panel
3. Drill hole in center of rivet and install screw with washer
4. Fit panel back on
5. Bang on panel with fist to see where it makes rattling noises
6. Remove panel again
7. Glue small sections of carpet padding (available at Home Depot) on the sections of the door panel that rattle

If you still have problems with the panel making creaking noises, it's probably the lower edge rubbing on the door sill. You can stick a velcro strip (fuzzy side) along the bottom edge of the door. It works and is hardly noticeable.

I think speedyturbo has the right answer - just wing it. You really should be able to do it yourself. It's no that hard to take the door panels off - maybe 10 to 15 minutes the first time and 5 minutes thereafter. From there it's just a matter of improvising - find things that seem loose and glue and wedge and tape, etc. It's hard to really even guess how long a mechanic could take on it.

It does not seem that easy for novice. I once worked on exterior door handle with the instruction from MB service CD, but I could not install it correctly. While I was trying again and again, I activated anti-theft alarm system. I ended up calling MB roadside assistance. It was easy for the technician.

The instruction for MB service CD tells me to remove window crank, but my car has electric window switch.

The following steps look difficult.
=======================
10. Engage pull rod on door handle and insert door inside actuation on door inside plate (3 slots).

11. Fasten hand grip inside with screw.

Note: Screw on hand grip is micro-encapsulated. Either replace or screw in with a screw locking compound.
=======================

__________________
1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

Once you remove one panel, you can do them all. The service manual makes a lot of things seem harder than they actually should be. Do a search for 124 or 300E door panel removal. There were many threads that covered it in detail.

You should try the Haynes 124 manual - it's really quite good. It has pictures and rates each job by degree of difficulty. I have both the CD and the Haynes manual and find that sometimes one is good, and sometimes the other is good. But between the two of them you can usually figure out what they're trying to say. The Haynes manual is available throught MB club - 303-237-0911 - about $30 I think.

The W126 CD I have assumes you know a lot when it gives you directions, it was really writen for dealer techs.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200