I got you beat on this one I like 3 weeks ago had a nut and stud broke off the top of one of my HS rockers, went through the motor took out the intermediate shaft gear, and into the pan, I got lucky I still took off the manifold to look for it, first I used one of those Harbour freight camera's couldn't find it, that what I would suggest if you can't see it with that the manifold will have to come off and hopefully its not in one of your cylinders, better find it before you start it up though o your going to be in big trouble..