They're long out of production. Same problem as trying to find just the spindle.

Might be worth it to find a machine shop that can do heat treating, and see if they could machine a new spindle. Provide them with a crank arm, an end bolt, and a bearing, so they can check fit. I'd wrap as much of the arm as possible with some kind of a protective wrap, to keep it from getting scraped and nicked while it's at the shop.