I've been corresponding with a 6.2L diesel owner over a couple of weeks about the flywheel situation for the manual transmissions. Here is his most recent message, which I thought might help any others who may need these parts.

Hello, Jim.
Thought I would follow up with you on the solid mass flywheel on a 6.2 Diesel.
I finally contacted a vendor who really knows his stuff. Knows about the GM service Bulletins on them etc.

I talked to Lou at Phoenix Friction in New Jersey. They have a kit for the job with flywheel, clutch, bearing and bolts for $500 including shipping. I will update you on how well it works when the job is finished. Blessings.

Al Peterson
Web page: https://www.phoenixfriction.com/p-23224-04-163ck-solid-flywheel-conversion-clutch-kit-gm-65l-diesel-pickups-suvs-12-in.aspx