575 Rear Suspension Squeak

The squeaks in the rear suspension on my 2004 575M have progressed from annoying to embarrassing. After my 100 mile trip from the airport today it sounded like a 1970's Chevy 1 Ton work truck. I am expecting that something needs some grease/lubricant. Checked the manual, and nothing there. Looked under and around the rear end, and nothing was obvious. If this is something easy I would rather do it myself than drive it 90 miles and wait for some simple fix by the nearest facility. Any advice on how to fix this?