My parallel experience has been in trying to find cones for my XTR M950 rear hub. Within three years of building the wheel, it seemed obsolete. Local bike shops found a couple of "close" fits for the right cone, but not tight enough to seal up the hub. They didn't last long compared with the original. I found some replacements in England, and finally sucked it up and ordered three since I was paying a boatload for shipping. They apologized and said they only had two in stock and probably wouldn't be getting any more. I'm not a fan of this part of Shimano's marketing strategy.

Suggestions? Search the internet and hope for the best and close your eyes to the prices. Let's hope someone "local" has a better answer, as I've got the tandem hubs too.