If it went under the pump. It's going to the cam. Probably could get it easily be used its a larger bolt. If it dropped where the stc fitting is, pull the rear cover.
I would pull the pump if its not already out to see if you can visibly see it. I would also drain the oil and get a magnet in the pan to see if it made its way down there, hopefully it did.
You can pull the pans in 6.0's pretty easily without pulling the engine. I jack up the engine about 3/4" and I have plenty of room to remove it after pulling the pickup tube as well.
Like CTC DEEZUL said, I'm pretty sure it was on that upper pan. I went and bought a 24" flexible magnet tool and gave it a small curve, ran it down parallel to the firewall and then swept it back and forth SLOWLY so I could hear the snap when it made contact. I'm going to guess it was 3-4" toward the front of the motor; had a straight magnet before and would have never gotten it with that.
Thanks guys. I wasn't looking forward to jacking the motor up and dropping the pan, it's been low 20's and high teens here...sucks not having a shop or large enough garage.
It is amazing where parts end up and get found and on the flip side, don't get found. You probably have a bigger smile on your face than your Chucky avatar!
those flex magnets are the best thing ever... I've got two on my work truck. I fished a lock washer out of a 12v Cummins head one time. It would have been bad news if I hadn't. I've also fished bolts out of P-pumps with them. I know the satisfaction of that click all too well