Thanks -- I spoke too soon!

I did some further reading and learned that "cracked" and "oil leaked out, joint in state of self-destruct" are not necessarily the same thing. Which is nice, since two of the three are fine, just cracked. I'ts only one that's actually got "symptoms" I can hear, and feel in the axles when she's up on the lift.

But what I did understand is that once the boot is fully breached and the factory oil has started leaking out, it's too late to reboot. Not that you can't keep driving the car until you get that old familiar clunking, but it's an axle replacement next.

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Anthracite 1980 300D -- 64k original miles with a new engine, on the road again!
Silver 300D -- second owner, Sunny's old baby, Ilse, 210 miles,
Having to thin the herd….
Silver 1983 300SD -- second owner, 325k miles
Gold 1981 300D -- well-traveled, solid little car
Beige 1984 300D -- 292k miles, grease machine, parting out
Seafoam green 1981 300SD -- 250k, windshield frame damage
too many assorted w123 & w126 cars, parts cars, and extras