Cut a thin piece of brass shim 12 - 15 thou and place under the pad. Cut the strip long enough to allow a 1/2" bend over each end so the shim won't slip out and just the width of the backing. Let us know if this works for you.
Squeal is caused by the pad grabbing and letting go, an up and down motion in the caliper. reduce the space for this motion and the squeal should go away.

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1984 300SD turbo 126
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