My M1028 sat on a NG base in Arizona for 25 years with the windows rolled up. When I got it last year all the rubber had dry-rotted and cracked due to the extreme heat of the southwest climate. During my rebuild I replaced all the rubber components including vacuum hoses, but it never occured to me to inspect the harmonic balancer. I just looked at it and, sure enough, it appears to be shot as well. I am glad I saw this thread before pulling it out of the shop. Thanks to TMIKE for the link to the Diesel Page article.
Today I ordered a new model 800191 from Fluidampr. This is the correct model for the 6.2 according to Mr. Ivan Snyder at Fluidampr, who was very helpful on the phone. The total cost including shipping was $455 but Hey - this is a lot less than fixing a broke crank! Mr. Snyder explained that the gel-filled design of the Fluidampr product will compensate for crankshaft stress thoughout the entire frequency spectrum at any RPM, thereby smoothing up the engine completely. And the gel-filled design will never wear out.
I will post a follow-up after I get the product installed.