Thanks for the reply! Now I know why the tailpipe is rattling. 5/8 inch clearance will give enough room for normal movement of the tailpipe to prevent rattling. Now it's off to the dealer tomorrow to get the catalytic converter, exhaust and tailpipe installed correctly. By the way, the front part of the catalytic converter is almost up against the frame member in contrast to the left side converter that sits up farther from the frame member.

Sometimes you wonder about what kind of training a mechanic in a Mercedes dealership receives. It seems as though significant improvement is needed in this area.