Does your '98 E320 have rear brake sensors on both sides? Mine only has a sensor on the right side.
I'm sorry I can't offer any suggestions to solve your noise issue, other than it might be caused by non OE quality pads. I'm also curious what the minimum rotor thickness is for the '98 E320.
1998 Mercedes E320 110+k
2000 Chrysler Town & Country Limited 85+k
1972 Ford Mustang 180+k
1988 Ford Tbird Sport (gave to nephew at 245k...still going at 270+k)
1983 Ford Tbird (traded at 135k)