Depends where and on what are we talking about? We use flex discs on our drive lines and more like CV axles from the rear end so except for the steering box i wouldnt say you have to worry about u joints on 124 models. I may be off it is late. Someone correct me if I am please.
OP, your car doesn't have a U-joint, but uses flex discs. These are to be regularly inspected. If they're allowed to deteriorate you may sense vibration, but usually no noise (noise occurs at the point of failure). Unfortunately if it fails it can result in lots of collateral damage.
So if you have not had them inspected get that done. It's a visual test, cracks and deterioration require replacement. Do a search (here and on the net) and you'll find pictures of bad ones.
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