Larry, Thanks for the information. This happened on my '86 300 SDL. I did check the threads on the bolt and inside the crankshft, they are both fine. I did reassemble it and torqued the bolt back in at 200 ft. lbs. with some loctite. What is troubling me is that the balancer was slightly forward from the front edge of the crankshaft. It looked like the last person used the belleville washer to achieve this offset. This was evidenced by the marks on the washer. Should the edge of the harmonic balancer where the washers stack up line up flush with the end of the crankshaft. I put it back together but I am not sure if the balancer is supposed to be flush with the edge of the crank or offset the way it was. The service CD was not very clear on this. Is it possible that the harmonic balancer walked forward slightly for few seconds that it was running? Thanks, Tom