"A two-piece driveshaft links the transmission and rear axle through two flexible disks and one universal joint to

minimize driveline vibrations"

Ive just done some research having noticed some slight cracking in the rubber Flexible Coupling Disk (or donut) at the rear end of the propshaft. The front coupling is fine probably because it runs in - line where as the rear one takes some more flexing. Having checked out the MB info on this it seems that some SLK's have had failures of the part with catastrophic results so worth checking and changing if any signs of cracking. Some of our friends in USA have had to change these on the Xfire. This can be due to age/mileage or too much hard acceleration. It seems that while the standard SLK or standard Xfire can have this issue, the AMG/SRT versions eat these couplings for breakfast. I would recomend inspection and replacement if any signs of cracking around the bolt heads, especially if the miles are creeping up, and even more so on SRT models as mine has done only 33K and last only owner was a lady! The MB part numbers are different for standard SLK/Xfire and AMG/SRT as the more powerfull car has version which is much more beefed up. AMG version for SRT is part number 203 410 0215 £79.00+Vat from your local MB dealer.