Well, sort of a "smoking gun", I guess. The material around the pilot bushing was checked, and it is magnetic, as is the pilot bushing itself. When I had the drivetrain work done at the local Chevy dealership here, I specifically requested that a pilot bushing be installed instead of a pilot bearing. And that the bushing be non magnetic (non-ferrous). I said this to the tech directly. Obviously that last part was ignored.
I suppose I understand now why when I contacted Dale Earnhardt Jr Chevrolet, where that particular tech is now the shop foreman, why they never got back to me about bringing my car back into their shop to diagnose a drivetrain noise.
Everything I read concerning using a pilot bushing strongly recommended against using a pilot bushing made out of sintered steel instead of pure sintered brass. I guess now I know why.
