There are indeed clutch plates in an automatic transmission, but the way your first post was worded made me think of a standard manual shift transmission with a clutch. The clutch plates in a auto transmission will be in groups of 3 to five plates with a smooth steel plate between each clutch plate. I doubt that is your problem. I haven't read about such a problem in the Crossfire NAG1 trans So unless you transmission has been seriously abused or a total lack of maintenance I doubt you have a transmission "clutch chatter" problem. More than likely it is that central bearing and if that is the case you will want to replace the rubber boot that protects the splines on the driveshaft from dirt. The Mercedes part number is 202 411 04 97 which is a common replacement item and any Mercedes dealer with a decent parts/repair shop will have it in stock. You can pick it up for about $5.00 and it slips right on to the drive shaft when the central bearing is replaced.