I had my balancer/pulley come off at out 50 mph and it was not a pretty site. Fortunately all I lost was the radiator and the belts. It took me two days to find the balancer after it put dents in the floor board of my car and rolled off a couple 100yrds down the road. It could have been much much worse. They were able to put in a helicoil where one of the bolts was ripped out. They said if that wasnt possible it would need a whole new crank shaft. I'd hesitate to drive it any more that you already have until it is fixed.

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85 300TD Turbodiesel 299,376 miles