My KYB experience -
I put KYBs on my '72 250 many years ago. They rode hard and the front's lower mount loosened up causing a severe rattle. Replaced with Bilsteins.
Installed KYBs on a friends '87 300SE. They rode hard but my friend liked them. Otherwise, they lasted until he got rid of the car.
I put KYB Gas-Adjust all round on my '87 Isuzu Pickup. They worked fine for that vehicle. But the OE shocks were already non-gas KYBs.
My recently purchased '82 240D came with Gas-Adjust KYBs on the front. With new Michelins, properly inflated, they ride hard. Plus they're badly rusted, so I paid $80 for a pair of new Bilsteins, from a friend who sold a 300CD without using them. Haven't installed them on the 240D yet so I don't know how different they may perform.

Happy Motoring, Mark

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DrDKW