correct drive shaft flex disc

2006 Mercedes e350 base sedan with 7 speed tranny.  Need new flex disc.  I have called dealership and was given part number 0004110100 for front and 2114100415 for rear.  Parts man stated that since the part numbers change and their mechanics will get special bullitins on how to make new parts work for my car.  How can i get that information?  and can someone give me how to and additional info on making them work on my car.  Also do i need to change out anything else while down there?  My vin is wdbuf56j26a883114. Flex disc appear dry rotted and I have a vibration when driving 60-70 and have a thunk sound when turning left and also a hard thunk when going down steep hill. Thank You, Deb