11.1 S60 Detroit metal in oil, bull gear bearing?

We have an 11.1 S60 Detroit, our part time mechanic that helps me a few days a week changed the oil in it recently and pictured below was on the drain plug. Unfortunately he didn't keep the shavings so I could have a look. I pulled the accessory drive, bull gear looks okay not like it's been wobbling.

Any other quick checks I should do to try to locate the source? Only 364k on the clock but it's in a dump truck so it usually gets rode hard and put up wet.

 

That's what I thought too. Apparently someone hopped in and drove it several times after he changed the oil so I'll drain it and see if I can get some more metal I can have a better look at myself.

I'm doubting I'd see chunks that big from the compressor but that could be a possibility as well.

 

Drained the oil and had a look at the drain plug magnet, few more flakes. I'm definitely not letting the truck to go out any more until I can find the source, drove it in the shop today and that's as far as it'll go.

Dropped the pan, oil pump drive gear looked fine and didn't initially see anything that looked off around the pump but I'll have a closer look tomorrow. I think I'll pull the valve cover tomorrow and have a look on top, I'm hoping if the source was from on top I'll be able to see some more chunks and flakes of metal that didn't make it down the drains back to the pan. Will see how the bearings/shaft in the turbo feel as well. If I'm still not having any luck I guess it'll be time to pull the front cover and have a closer look under there.

Really wish our part time help hadn't thrown away the larger chunks he found in the first pic so I could see them for myself, but too late to worry over that now.