Crutchfield is a RIPOFF, though their site is extremely informative. So go to their site, find what you are looking for, then go to
www.carmedia1.com or
www.thezeb.com . They have much better prices, in some cases you will save a couple hundred on your purchase. More than likely you will need a changer with RF controls. Unless your factory radio has changer controls, you can find out the brand that makes the changers for MB, and hope there's a adapter prewired in your car. Good luck.