Unless you've had maintenance done that required the bolt and pulley be removed, I can't honestly imagine what would cause the threads on the bolt to have stripped, and it's kind of difficult to guess at what would have caused it even with work being done.

Is it possible that you were told the harmonic balancer had slipped, rather than the bolt being stripped? This is a common situation with these engines, which then makes the timing marks inaccurate, but it's relatively easy to work around temporarily. Is the truck running poorly now, and if so, what's the story on how it got that way. That info will help us be a lot more beneficial to helping you get back into the truck you love. <img src="/forums/images/graemlins/smile.gif" alt="" />

BTW, Welcome to the 'Wire!

James