I had a ticking noise coming from the center of my Mercedes C32 console area. (trying to use search engine keywords here) The ticking was slight and would speed up as I drove. Didn't effect car performance but was extremely irritating. Anyway my brother pulled this info from some type of online mechanic reporting system. We removed the heat shield and sure enough insulation was hitting the drive shaft.
Here's how to fix the problem
October 8, 2004
Scrapping Noise from Transmission Tunnel Area
If you receive customer reports in the above model vehicles of a
scraping noise from the area of the transmission tunnel, the insulation
above the transmission may have warped and is scraping on the propeller
shaft. To resolve, perform the below procedure.
1. Make a bracket to support the transmission tunnel insulation by
taking a strip of aluminum approximately 2 mm thick.
2. Cut the strip 40 mm wide and 220 mm long.
3. Drill a 6.5 mm diameter hole in the center (Figure 1).
Warning! Under body components may be hot, use caution.
4. Detach central heat shield above exhaust system and slide toward the
rear (Figure 2).
5. Remove nut retaining insulation (Figure 3, arrow).
6. Bend aluminum strip to conform with tunnel contour.
7. Fit aluminum strip on threaded stud and reinstall original nut.
8. Reinstall central heat shield above exhaust system.
Hope this helps anyone in the future