Check with @Jake Kuhn - I purchased a NOS cross shaft from him for a similar deck a while back..
Another thought - that area can either be welded up & turned or cut for a sleeve... done right it should be good as new...
This is the "517-H" (520-H with Kohler KT17 Series II). New pair of rear tires, Tach-a-matic brackets, all tins and headlight bezels will be included. Swept front axle and (I'm pretty sure) it has the steering reduction.
Do check the overhung ends of the shaft for runout. I had to replace mine because one end was bent - that made the gear revolve in a "Potato Chip" motion.