Surprised no one has responded to this as of late...

Buy some "brake paste" available at most auto shops for under $10. It should be applied to the outer face of the pads (not the disc contact side) prior to installation.

Forgot to do this when I did the rears on my ML and now they squeal a little.

I replaced the pads on my W124 last year and they howled badly when making slow stops! So I pulled them off and applied the paste to the pads and the squealing dissappeared completely!

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car