My old Nissan went 215K with no pulley problems. GM has made literally millions of these with the rubber in them, and they've been working fine for years. Without the rubber they would transfer too much crankshaft vibration to the belt and the accessories. The problem must be specific to this part; a rubber bonded balancer is not unique.

__________________
Lenny

There are only three sports: bullfighting, motor racing and mountaineering; all the rest are merely games. --Ernest Hemingway

'10 GL550/'04 BMW 545/'99 BMW 323/'98 ML320/'87 VW GTI (race)