Yes, the front brakes could squeal too. But, if you don't get a change in the squeal on applying the brakes, that would tend to lead me toward the wheel bearings.

You should be able to tell what's going on by jacking up the front wheel on that side and spinning it around.

Ken300D

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