I replaced my original Sachs with Bilsteins (front) at 150K on an advice of an alignment specialst and over the advice of my regular mech. The problem was not up and down bouncing (they behaved like a brand-new KYB's), but the sideways movement of the shaft. Now the whole suspension feels tighter and there is an improvement in handling over a spectrum of bumps (i.e. it's the same decisive motion-thump over 1/2" bump and a 3" pothole). Getting ready to do the same with my rears this weekend. And no, none of them leaked or indicated any wear. I read somewhere that the original OE mid-80's shocks are good for 150-200K.
1985 190D 2.2l Sold-to Brother-in-law
1996 Mustang 3.8l -"thinks it's a sports car"
1988 Grand Wagoneer - Sold (good home)
1995 Grand Cherokee Ltd -"What was I thinking??!!"