I plan to replace the front struts soon. I've finally found a good summary that eliminates some of the confusion about the myriad part numbers available.

https://www.benzworld.org/threads/strut-and-shock-compatibility-across-the-range.1701801/

Post entry #8 is the one that helped me.

Jerry, I'm running Bilstein Strut Assembly; Front; Heavy Duty 22003614 on my E300D and I love them. The suspension feel will be a huge selling point for the next owner (hopefully soon).

-Andrew

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'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter

Replacing the struts makes a big difference on a post 150k mile W124. It is relatively cheap and fairly easy DIY once car is in air.

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-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991

Yes, there is quite a big difference between the Bilstein offerings, I've experienced them all.

I got a '92 260E once in great condition but I wasnt happy with the ride then, not how I remembered them to ride. After cross checking part numbers I saw they were HD fronts and rough road rears. I replaced them with comforts and it transformed the ride, so much better.

Prior to that I tried sports with H&R springs with 17" wheels on an '86 300D. It's been 20 years but I do remember they were quite the combination of ride and handling. I loved them! Apparently they have the same damping rates as the HD but in a yellow body more suited for shorter sport springs. IMO HD/sport damping is great with stiff springs but I dont like them with stock springs, harsh ride with not much improvement in handling over stock. A lot of people like the HD's though, just not for me.

My current '90 300D has comforts up front. I was gonna put new comforts in the rear but surprisingly, the original 1990 shocks are still good! I feel my old 260E rode better so am looking at springs now. There are a lot of part numbers and they are more confusing than dampers IMO lol!

Not that great reference.
I have 124.128 with om603, so basically made 1987 300D from 1992 300D.
EPC calls for 24-013857 rear, which is HD.
Bilstein website calls for 24-015189 rear, which is comfort. It is also found on 1987 300D and some gas cars. So I got this one, even though my 1992 called for HD, and apart from lower price, the ride is great. Less thumping on speed bumps.
Prior to replacement, I had B6 HD in there, still kinda good.

I have heavy duty Bilsteins on my W115 and W124. Absolutely love them. Major misconception floating around is that they make the ride harsher. Simply untrue. But they do make it much tighter and far more enjoyable to drive!

Make sure you buy the rear heavy duty shock absorber dust covers from Mercedes. Bilstein doesn't supply them but Benz has them in stock.

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Why I will never do business with "DieselKraut" again

http://www.peachparts.com/shopforum/mercedes-benz-used-parts-sale-wanted/378935-why-i-will-never-do-business-dieselkraut-again.html

^I've replaced HD's for comforts on a few 124's. There is a definite negative effect on ride over road cracks and potholes.

On the other hand I agree HD's have a less floaty feel at high speed, and a bit less sway in the twisties.

"Harsh" may be too harsh a word indeed lol!

For how I see and use these cars I personally prefer the comforts though.

H&R Springs with Bilstein B8 struts is by far my favorite setup for a W124 suspension. Car rides like its on rails compared to stock and I think it looks fantastic too.