500 SEL '82Euro has driveline clunk on downshifting of trany only; installed new front/rear flex kits, trany mount, differential mount and resealed the trany but clunk still there. Driveshaft support is good; bearing is good. No apparent wheel bearing noise; all wheel lug nuts tight. Would appreciate any ideas about cause/ solution?

You have started where I would have started with such a problem. Perhaps next item should be to change the rear differential fluid. Probably needs to be done anyway if its never been changed.

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ARVY

1999 E430
1999 C230 Kompressor
1992 300E (write-off)
1984 190D 2.2 (sold)

Is there a u-joint somewhere in the driveshaft (Propeller shaft) of the 126 that may cause the driveline clunk? If so where? how to remove?