Yep, it's known to happen, even on stock trucks. Get with Guy Tripp of SoCal Diesel or Eric Merchant of Merchant Automotive and they can better describe the fix for it. My understanding is they machine a keyway into the cam/gear in order to handle the torsional load that sheared the pin. If I understand it right, that pin was never meant to hold a torsional load but rather was a place holder/locator pin. It's been a while since I read up on it so that might not be just right but I think it's close.
Good luck. And if you get a chance, pictures are always nice to see and learn from.
C-ya