The front flex disk is typically cracked by 60K miles. The MB maintenance system says to inspect them at the 15K mile maintenance. As they deteriorate the driveline gets sloppy, which can usually be felt by the driver.

I've never heard of one completely disintegrating, so I suspect that your car has not had the proper maintenance inspections, or the problem would likely have been discovered before it got to the point where it disintegrated.

The rear disk is a much more robust design and much longer lived.

Duke