What's the symptoms both from a feel and sound perspective of a bad rear axle on a W124 wagon?

More importantly, how do I diagnose a bad rear-axle vs. bad rear diff.

I have a fast "waa-waa" sound that comes on between 45-80mph ONLY during accelleration.

I had the car on jack-stands, and could hear it (not feel it) both with and without wheels on. It sounds like from both the left & right sides. I felt a vibration in the rear-diff, but I don't know if that's normal or not.

FWIW, the rear bearings have been replaced about a year ago.

Would worn rear-diff bushings produce the same symptom (e.g., waa-waa sound on acceleration ONLY, goes away when lifting off the gas)?

TIA,
:-) neil
1988 360TE AMG
1993 500E

Perhaps the driveshaft center support bearing?

Feel any vibration at the center drivetrain hump inside the car?

Another related idea that I read here is a swap of the half-shafts. When you do that you start almost over again on CV joint component wear.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Neil, be very careful about this with a limited slip. I think you should take it out and rebuilt it. What I believe is happening is the differential carrier bearings might be going bad which causes the gear teeth to not "hit" in the right spot and they make a whine/humming noise especially when you decellerate. Acceleration I havent heard it as much.

But there are shims on the side of the differential so that everything is aligned. I think that Bergwerks knows how to shim mercedes differentials, since I know you are good friends with Carl, you should talk to him about what I am bringing up, and see what he thinks in light of what I think.

Let us know.

Speaking of limited slips, have you gotten the 3.27 190E limited slip ready for me?

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Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.