OP here with an update.
Took the air intake system apart yesterday. Physically checked them for cracks and soft spots. Found none. While it was apart checked for play in turbo. Found a small amount of radial play, no end play. So I put everything back together and started the truck. Ran for about five minutes then a rattling sound started, sounded exactly like a wrench had been left on top of the engine. After about ten minutes of running I heard a grinding sound. This one sounded just like gravel in the brakes, but I wasn't moving.
Near as I can tell, the turbo needs replacing. Next available appointment at the shop is June 8.
There is another mechanic specializing in diesels, Cummins specifically. I will also talk with him to see about possible upgrades.
Dan