If this fails, the engine falls down until it hits the back of the transmission on the crossmember, or the remains of a metal part of the mount. The driveshaft and the exhaust can both be out of line if this happens, with unpredictable results. Either item, or the engine or trans itself, can contact the frame or body. Anytime this happens, there's SIGNIFICANT vibration transferred to the body, creating noise, squeaks and rattles.
Normally everything is isolated by some kind of a rubber mount: i.e. engine mounts, center driveshaft bearing carrier, rubber exhaust hangers, even the rubber bushings in the shifter serve to isolate noise and vibration.
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Rob Bareiss, New London CT ::: 'Roterande Fläkt Och Drivremmar!'